On 29/5/2026 9:53 pm, Noddy wrote:
On 29/05/2026 6:01 pm, jonz wrote:It was all so long ago and so many racing car breakages later I can
On 29-May-26 3:05 PM, jonz wrote:
-a-aThe 4A-GE(20), having a *5 valve per cylinder head*,
~~~~~~~~~~~~~~~~~would be actually creating valve loft to increase cylinder fill
at high RPM.
Nope, because of smaller/lighter valve size, the chances of lofting
in a 5 valve are reduced.... one of the reasons for a 5 valve design
in the first place!.
This has been done to death, and the more this mental midget goes on
with this nonsense the more clueless he reveals himself to be.
The engine failed catastrophically on the turn in to the chase on
Conrod Straight at Mount Panarama on the 7th lap of a race. Prior to
that race the car had done various practice sessions, a full day of
test and tuning at another track (winton) and two separate full dyno
sessions without any hint of an issue.
The engine had *one* valve fail. It was *not* "creating valve loft to
increase cylinder fill" which is about as nonsensical a claim as one
can make. It failed because it stuck a valve in it's guide at full
lift which broke the valve off at the stem, punched it back up into
the head and forced the piston to rock in it's bore which immediately
split the bore and filled the cylinder with coolant.
Daryl may still have the video of the thing when it failed where the
engine changed note and trailed a huge plume of white smoke out of
it's pipe. It was an instant component breakage which is not unknown
in the world of motorsport :)
barely remember the details, things break on the track that rarely
fail on the public road, its just how it is in motorsport.
At the moment we are working on a Westfield, a club member died a
couple of months ago and his wife wants to sell the car so we are
trying to get it roadworthy, first test came back with 3 faults the
most difficult to sort is the right rear brake caliper which is off a Peugeot 504, getting parts for a 40+ yr old French car in Australia is proving to be rather difficult although on Friday we finally managed
to find a helpful wrecker that said he might have a sh caliper and a
rebuild kit.
On 30/05/2026 10:22 am, Daryl wrote:
On 29/5/2026 9:53 pm, Noddy wrote:
It was all so long ago and so many racing car breakages later I can
Daryl may still have the video of the thing when it failed where the
engine changed note and trailed a huge plume of white smoke out of
it's pipe. It was an instant component breakage which is not unknown
in the world of motorsport :)
barely remember the details, things break on the track that rarely
fail on the public road, its just how it is in motorsport.
Yep. Not for the mental case though. He has all the answers. Of course,
when you come up with 17 different explanations for an issue that you
had no personal experience with one way or the other you're bound to hit
one a good one eventually, right?
It's quite amazing really. With his quite extraordinary powers of
failure analysis you have to wonder why his services aren't in high
demand all over the world :)
At the moment we are working on a Westfield, a club member died a
couple of months ago and his wife wants to sell the car so we are
trying to get it roadworthy, first test came back with 3 faults the
most difficult to sort is the right rear brake caliper which is off a
Peugeot 504, getting parts for a 40+ yr old French car in Australia is
proving to be rather difficult although on Friday we finally managed
to find a helpful wrecker that said he might have a sh caliper and a
rebuild kit.
If you need piston seals there's a guy in Brooklyn I've used a couple of times to cut new seals on a CNC machine for things like callipers that
parts are no longer available for. His business is Hydraulic Seals Australia, and his number is 9314-1620.
He's a decent bloke. Quick turn around and decent prices.
On 29/05/2026 6:01 pm, jonz wrote:
On 29-May-26 3:05 PM, jonz wrote:
-a-aThe 4A-GE(20), having a *5 valve per cylinder head*,
~~~~~~~~~~~~~~~~~would be actually creating valve loft to increase cylinder fill at
high RPM.
Nope, because of smaller/lighter valve size, the chances of lofting in
a 5 valve are reduced.... one of the reasons for a 5 valve design in
the first place!.
This has been done to death, and the more this mental midget goes on
with this nonsense the more clueless he reveals himself to be.
The engine failed catastrophically on the turn in to the chase on Conrod Straight at Mount Panarama on the 7th lap of a race. Prior to that race
the car had done various practice sessions, a full day of test and
tuning at another track (winton) and two separate full dyno sessions
without any hint of an issue.
The engine had *one* valve fail. It was *not* "creating valve loft to
increase cylinder fill" which is about as nonsensical a claim as one can make. It failed because it stuck a valve in it's guide at full lift
which broke the valve off at the stem, punched it back up into the head
and forced the piston to rock in it's bore which immediately split the
bore and filled the cylinder with coolant.
Daryl may still have the video of the thing when it failed where the
engine changed note and trailed a huge plume of white smoke out of it's pipe. It was an instant component breakage which is not unknown in the
world of motorsport :)
On 29/5/2026 9:53 pm, Noddy wrote:
On 29/05/2026 6:01 pm, jonz wrote:
On 29-May-26 3:05 PM, jonz wrote:
-a-aThe 4A-GE(20), having a *5 valve per cylinder head*,
~~~~~~~~~~~~~~~~~would be actually creating valve loft to increase cylinder fill
at high RPM.
Nope, because of smaller/lighter valve size, the chances of lofting
in a 5 valve are reduced.... one of the reasons for a 5 valve design
in the first place!.
This has been done to death, and the more this mental midget goes on
with this nonsense the more clueless he reveals himself to be.
The engine failed catastrophically on the turn in to the chase on
Conrod Straight at Mount Panarama on the 7th lap of a race. Prior to
that race the car had done various practice sessions, a full day of
test and tuning at another track (winton) and two separate full dyno
sessions without any hint of an issue.
Odd, Daryl clearly stated way back that it was running down conrod
straight when it blew. I have been mentioning conrod straight many
times and he has never questioned it. This looks to me like your
standard modus operandi of waiting a year or three and then, when
memories have faded, *alter the data* over to where you need it to be.
If Daryl had not made that point, I would never have arrived at the
valve lofting conclusion.-a >
The engine had *one* valve fail. It was *not* "creating valve loft to
It only takes one. The next one might have been seconds away but once
that first one lets go, nothing more matters because the engine is
dead, dead, dead!
Next point, all high performance high revving engines rely on a degree
of lofting to gain those little bits of extra performance. The
benefits of valve lofting were discovered and utilised first in the motorcycle racing industry when they first moved to OHV. It is not deliberately used in today's OHC engines due to the lightweight valve trains. Today's torque curves are achieved using precise static valve
lift profiles and variable valve timing rather than relying on dynamic lofting. That said, a very high speed run down conrod straight in a
high gear at WOT is where you are most likely to over rev the engine
and see some unwanted lofting. This is a point I made at the very
beginning when Daryl first mention the point at which the failure
occurred.
increase cylinder fill" which is about as nonsensical a claim as one
can make. It failed because it stuck a valve in it's guide at full lift
It failed because the head fell off due to piston contact and
subsequent overheating at the fillet, the hottest point of the valve. Happens in moments when at WOT.
which broke the valve off at the stem, punched it back up into the head
Of course it would punch it up there. A loose valve head hasn't a lot
of room in a combustion chamber when the piston is moving at 15-30 Mps
at high RPM and acting like the meanest hammer you would ever see.
and forced the piston to rock in it's bore which immediately split
the bore and filled the cylinder with coolant.
Irrelevant, that all happened post the initial cause.>
Daryl may still have the video of the thing when it failed where the
engine changed note and trailed a huge plume of white smoke out of
it's pipe. It was an instant component breakage which is not unknown
in the world of motorsport :)
Not when you take out piston to valve clearance and then create valve lofting
through over revving because you (a) reduced clearance with a shim
head gasket
and (b) didn't take counter measures, ie. lighter valves, stronger
springs, different cam profile. It happens to clowns like you all the
time.
Conrod straight is known for such failures because, quite simply, it
is possible to over rev the engine when running downhill, WOT, at speed.
Xeno wrote:
On 29/5/2026 9:53 pm, Noddy wrote:
On 29/05/2026 6:01 pm, jonz wrote:
On 29-May-26 3:05 PM, jonz wrote:
-a-aThe 4A-GE(20), having a *5 valve per cylinder head*,
~~~~~~~~~~~~~~~~~would be actually creating valve loft to increase cylinder fill >>>>>>> at high RPM.
Nope, because of smaller/lighter valve size, the chances of lofting
in a 5 valve are reduced.... one of the reasons for a 5 valve design
in the first place!.
This has been done to death, and the more this mental midget goes on
with this nonsense the more clueless he reveals himself to be.
The engine failed catastrophically on the turn in to the chase on
Conrod Straight at Mount Panarama on the 7th lap of a race. Prior to
that race the car had done various practice sessions, a full day of
test and tuning at another track (winton) and two separate full dyno
sessions without any hint of an issue.
Odd, Daryl clearly stated way back that it was running down conrod
straight when it blew. I have been mentioning conrod straight many
times and he has never questioned it. This looks to me like your
standard modus operandi of waiting a year or three and then, when
memories have faded, *alter the data* over to where you need it to be.
If Daryl had not made that point, I would never have arrived at the
valve lofting conclusion.-a >
The engine had *one* valve fail. It was *not* "creating valve loft to
It only takes one. The next one might have been seconds away but once
that first one lets go, nothing more matters because the engine is
dead, dead, dead!
Next point, all high performance high revving engines rely on a degree
of lofting to gain those little bits of extra performance. The
benefits of valve lofting were discovered and utilised first in the
motorcycle racing industry when they first moved to OHV. It is not
deliberately used in today's OHC engines due to the lightweight valve
trains. Today's torque curves are achieved using precise static valve
lift profiles and variable valve timing rather than relying on dynamic
lofting. That said, a very high speed run down conrod straight in a
high gear at WOT is where you are most likely to over rev the engine
and see some unwanted lofting. This is a point I made at the very
beginning when Daryl first mention the point at which the failure
occurred.
increase cylinder fill" which is about as nonsensical a claim as one
can make. It failed because it stuck a valve in it's guide at full lift
how does he know? could have been valve float
It failed because the head fell off due to piston contact and
subsequent overheating at the fillet, the hottest point of the valve.
Happens in moments when at WOT.
only if the valve is open during compression
which broke the valve off at the stem, punched it back up into the head
Of course it would punch it up there. A loose valve head hasn't a lot
of room in a combustion chamber when the piston is moving at 15-30 Mps
at high RPM and acting like the meanest hammer you would ever see.
and forced the piston to rock in it's bore which immediately split
the bore and filled the cylinder with coolant.
must have been an aluminum block then
Irrelevant, that all happened post the initial cause.>
Daryl may still have the video of the thing when it failed where the
engine changed note and trailed a huge plume of white smoke out of
it's pipe. It was an instant component breakage which is not unknown
in the world of motorsport :)
Not when you take out piston to valve clearance and then create valve
lofting
valve lofting done properly won't cause piston to head contact, only
valve float or bounce does
through over revving because you (a) reduced clearance with a shim
head gasket
has he ever said he used a shim head gasket?
and (b) didn't take counter measures, ie. lighter valves, stronger
springs, different cam profile. It happens to clowns like you all the
time.
Conrod straight is known for such failures because, quite simply, it
is possible to over rev the engine when running downhill, WOT, at speed.
Xeno wrote:
increase cylinder fill" which is about as nonsensical a claim as one
can make. It failed because it stuck a valve in it's guide at full lift
how does he know? could have been valve float
It failed because the head fell off due to piston contact and
subsequent overheating at the fillet, the hottest point of the valve.
Happens in moments when at WOT.
only if the valve is open during compression
https://ibb.co/mcKy0q5
https://ibb.co/cwxR1yL
and forced the piston to rock in it's bore which immediately split
the bore and filled the cylinder with coolant.
must have been an aluminum block then
Not when you take out piston to valve clearance and then create valve
lofting
valve lofting done properly won't cause piston to head contact, only
valve float or bounce does
through over revving because you (a) reduced clearance with a shim
head gasket
has he ever said he used a shim head gasket?
On 31/5/2026 3:34 pm, Axel wrote:
Xeno wrote:
On 29/5/2026 9:53 pm, Noddy wrote:
On 29/05/2026 6:01 pm, jonz wrote:
On 29-May-26 3:05 PM, jonz wrote:
-a-aThe 4A-GE(20), having a *5 valve per cylinder head*,
~~~~~~~~~~~~~~~~~would be actually creating valve loft to increase cylinder fill >>>>>>>> at high RPM.
Nope, because of smaller/lighter valve size, the chances of
lofting in a 5 valve are reduced.... one of the reasons for a 5
valve design in the first place!.
This has been done to death, and the more this mental midget goes
on with this nonsense the more clueless he reveals himself to be.
The engine failed catastrophically on the turn in to the chase on
Conrod Straight at Mount Panarama on the 7th lap of a race. Prior
to that race the car had done various practice sessions, a full day
of test and tuning at another track (winton) and two separate full
dyno sessions without any hint of an issue.
Odd, Daryl clearly stated way back that it was running down conrod
straight when it blew. I have been mentioning conrod straight many
times and he has never questioned it. This looks to me like your
standard modus operandi of waiting a year or three and then, when
memories have faded, *alter the data* over to where you need it to
be. If Daryl had not made that point, I would never have arrived at
the valve lofting conclusion.-a >
The engine had *one* valve fail. It was *not* "creating valve loft to
It only takes one. The next one might have been seconds away but
once that first one lets go, nothing more matters because the engine
is dead, dead, dead!
Next point, all high performance high revving engines rely on a
degree of lofting to gain those little bits of extra performance.
The benefits of valve lofting were discovered and utilised first in
the motorcycle racing industry when they first moved to OHV. It is
not deliberately used in today's OHC engines due to the lightweight
valve trains. Today's torque curves are achieved using precise
static valve lift profiles and variable valve timing rather than
relying on dynamic lofting. That said, a very high speed run down
conrod straight in a high gear at WOT is where you are most likely
to over rev the engine and see some unwanted lofting. This is a
point I made at the very beginning when Daryl first mention the
point at which the failure occurred.
increase cylinder fill" which is about as nonsensical a claim as
one can make. It failed because it stuck a valve in it's guide at
full lift
how does he know? could have been valve float
It failed because the head fell off due to piston contact and
subsequent overheating at the fillet, the hottest point of the
valve. Happens in moments when at WOT.
only if the valve is open during compression
Or if the valve got a light tap from the piston, enough so the valve
would no longer seat and seal during the compression and power
strokes. That would lead to a loss of valve head cooling, an instant overheat due to burning>
which broke the valve off at the stem, punched it back up into the
head
Of course it would punch it up there. A loose valve head hasn't a
lot of room in a combustion chamber when the piston is moving at
15-30 Mps at high RPM and acting like the meanest hammer you would
ever see.
and forced the piston to rock in it's bore which immediately split
the bore and filled the cylinder with coolant.
must have been an aluminum block then
No, all the 4A-GE engines have cast iron blocks. The cylinder head is
alloy however - and it has 5 valves per cylinder.>
Irrelevant, that all happened post the initial cause.>
Daryl may still have the video of the thing when it failed where
the engine changed note and trailed a huge plume of white smoke out
of it's pipe. It was an instant component breakage which is not
unknown in the world of motorsport :)
Not when you take out piston to valve clearance and then create
valve lofting
valve lofting done properly won't cause piston to head contact, only
valve float or bounce does
Correct. *Done properly* are the operative words. The engine has to be considered as a system and any single change will affect the system
and its related components. Therefore any change has to be sympathetic
to all aspects of the engine, not just one single aspect.>
through over revving because you (a) reduced clearance with a shim
head gasket
has he ever said he used a shim head gasket?
Yes, he did.
That was my point from the beginning. Engines typically have up to
0.100" piston to valve *static* clearance. Performance engines, like
the $A-GE(20), typically have a bit less but employ much more rigorous *valve control*. Take some of that clearance, up to 0.020" in the case
of a shim head gasket, and the piston can hit the valve in extreme circumstances - and flat out on conrod straight is an extreme
circumstance. When Daryl indicated the location of the blowup, the
cause became immediately apparent to me. Affect valve cooling in such
a circumstance and the valve head will overheat and drop off *in
seconds*. That, of course, will trigger a catastrophic failure, as
could be seen in the photos.
Darren claims he just fitted the head. I call bullshit on that. If I
were asked to do a job like that I would have pulled all the valves
and checked them out and I would have checked their sealing and
clearances.
I would have likely fitted lighter and stronger valves that were much
less likely to loft and/or bounce.
What Darren forgot was that removing head gasket thickness
automatically increases the compression ratio. That's done in order to increase power and that power will come at increased revs. Therein
hangs the tale. >
and (b) didn't take counter measures, ie. lighter valves, stronger
springs, different cam profile. It happens to clowns like you all
the time.
Conrod straight is known for such failures because, quite simply, it
is possible to over rev the engine when running downhill, WOT, at
speed.
Xeno wrote:
has he ever said he used a shim head gasket?
Yes, he did.
no, he just said he used the proper gasket
That was my point from the beginning. Engines typically have up to
0.100" piston to valve *static* clearance. Performance engines, like
the $A-GE(20), typically have a bit less but employ much more rigorous
*valve control*. Take some of that clearance, up to 0.020" in the case
of a shim head gasket, and the piston can hit the valve in extreme
circumstances - and flat out on conrod straight is an extreme
circumstance. When Daryl indicated the location of the blowup, the
cause became immediately apparent to me. Affect valve cooling in such
a circumstance and the valve head will overheat and drop off *in
seconds*. That, of course, will trigger a catastrophic failure, as
could be seen in the photos.
Darren claims he just fitted the head. I call bullshit on that. If I
were asked to do a job like that I would have pulled all the valves
and checked them out and I would have checked their sealing and
clearances.
unless you had full confidence in whoever did the head and knew what was done
I would have likely fitted lighter and stronger valves that were much
less likely to loft and/or bounce.
What Darren forgot was that removing head gasket thickness
automatically increases the compression ratio. That's done in order to
increase power and that power will come at increased revs. Therein
hangs the tale. >
anyhow, since he only fitted the head as supplied, and used the correct gasket, the engine failure is hardly his fault
On 1/06/2026 10:51 am, Axel wrote:
Xeno wrote:
has he ever said he used a shim head gasket?
Yes, he did.
no, he just said he used the proper gasket
That's right Felix. The gasket used was Toyota competition head gasket
made specifically for that engine. As I mentioned, I have never
claimed to have used a "shim" head gasket, and for the specific reason
being that such a term isn't in my vocabulary. There is no such thing
as a "shim head gasket". There are only head gasket shims, and head
gaskets. You cannot run a head gasket shim on it's own, and they are
not designed to seal.
As you can see here, regardless of being told the facts of the matter,
and more than once I might add, he *still* persists in ignoring
reality and inserting his own bullshit.
This is the moron you're trying to argue sense with.
That was my point from the beginning. Engines typically have up to
0.100" piston to valve *static* clearance. Performance engines, like
the $A-GE(20), typically have a bit less but employ much more
rigorous *valve control*. Take some of that clearance, up to 0.020"
in the case of a shim head gasket, and the piston can hit the valve
in extreme circumstances - and flat out on conrod straight is an
extreme circumstance. When Daryl indicated the location of the
blowup, the cause became immediately apparent to me. Affect valve
cooling in such a circumstance and the valve head will overheat and
drop off *in seconds*. That, of course, will trigger a catastrophic
failure, as could be seen in the photos.
Darren claims he just fitted the head. I call bullshit on that. If I
were asked to do a job like that I would have pulled all the valves
and checked them out and I would have checked their sealing and
clearances.
unless you had full confidence in whoever did the head and knew what
was done
As mentioned, the head was delivered to my place fully assembled
having been done by other people, and any fault the head may or may
not have had is between the owner and the head people to argue over.
It's not my job to check *other* people's work.
This bloke is living ion fantasy land. He would never have done a job
like this because (a) it's out of his depth which is abundantly clear
from his moronic comments, and (b) if he was dismantling and checking
every single component that he had nothing to do with he'd spend an *extraordinary* amount of time not getting paid :)
I remember him making a similar nonsensical outburst some years ago
when I mentioned that the bloke next door had blown the diff in his
105 series Land Cruiser and I was fitting a used diff centre to it. He
made a *huge* song and dance about how "a real mechanic would rebuild
the original diff", while having zero appreciation of the fact that
all the owner was interested in paying for was the cheapest way to get
the car back on the road.
The funniest part was when he claimed that in the past he would have
ignored customer requests and told them to fuck off if they didn't
want to do what he recommended, and it was interesting to note that he
had no answer to the question of when he was ever in a position to
deal directly with customers.
Such is the level of delusion :)
I would have likely fitted lighter and stronger valves that were
much less likely to loft and/or bounce.
What Darren forgot was that removing head gasket thickness
automatically increases the compression ratio. That's done in order
to increase power and that power will come at increased revs.
Therein hangs the tale. >
anyhow, since he only fitted the head as supplied, and used the
correct gasket, the engine failure is hardly his fault
He's been told this *many* times Felix, but his inferiority complex
prevents him from accepting that. Instead, he'll keep inventing
utterly ridiculous excuses to try to lay the blame at my feet while achieving nothing other than making *himself* look completely clueless
in the process.
Such is the state of his mind.
On 31/05/2026 3:34 pm, Axel wrote:
Xeno wrote:
how does he know? could have been valve floatincrease cylinder fill" which is about as nonsensical a claim as one
can make. It failed because it stuck a valve in it's guide at full lift >>
It *wasn't* "valve float" Felix, and to make such a claim shows that you
have no understanding of what it is or how it works.
It failed because the head fell off due to piston contact and
subsequent overheating at the fillet, the hottest point of the valve.
Happens in moments when at WOT.
only if the valve is open during compression
Nope. As I said, it was a valve as full lift striking the piston which
caused the engine failure. That much is obvious to anyone with an ounce
of experience (which would *not* be your mental mate). The only point of conjecture is why the valve was *at* full lift when the piston hit it,
and there are a few reasons for that. It could have broken a valve
spring, it could have dropped a collet, and it could have had a tight
guide that saw the valve "grab". What it most definitely was *not* was a result of "loft" or a mechanical piston to valve clearance issue.
I have shown these pictures before Felix, but as usual you have the retention ability of a dead goldfish. This is the type of valve failure
you get from a minor piston to valve clearance issue, and it's commonly
seen whenever an interference type engine breaks a timing belt:
https://ibb.co/mcKy0q5
As can be seen, the valves in this picture are not bent severely, but certainly bent enough to cause an instant loss of compression resulting
in a dead cylinder. That's *not* what happened in this case.
This is what happened:
https://ibb.co/cwxR1yL
You can't see it clearly in this pic, but the valve had been snapped off half way up it's stem and then hammered back up into it's port pocket.
It was an instant catastrophic failure that was a result of a component breakage, and it gave zero warning before it occurred.
Despite the nonsensical claims of your mental mate, this is *not* what happens if a valve has been bent slightly from a piston to valve
clearance issue, as any kind of bent valve will cause an instant
compression loss which will be apparent to the driver. And I can tell
you that had such a compression loss occurred Les would have shut the
car down and got it into the pits to investigate :)
and forced the piston to rock in it's bore which immediately split
the bore and filled the cylinder with coolant.
must have been an aluminum block then
Wrong again Felix. Cast iron block, and split bores in cast iron blocks
are not that uncommon. It's very easy to do with you have a piston and
valve remains fighting for an area that is not big enough to accommodate them.
I used to split bores on Chev V8 engines from running 40lbs of boost
thought a supercharger :)
Not when you take out piston to valve clearance and then create valve
lofting
valve lofting done properly won't cause piston to head contact, only
valve float or bounce does
Correct. This is a perfect example of your clueless mental mate trying
to pass off technical terms he doesn't understand as explanations for
faults he has no idea about.
through over revving because you (a) reduced clearance with a shim
head gasket
has he ever said he used a shim head gasket?
Nope. That's his invention. The engine used a Toyota competition head
gasket which is made specifically for this particular engine. It's make
to raise the compression by around half a point by being thinner than a regular composite gasket. It is not a "shim", and I've never used that
term. That's something he made up. Either way, it's irrelevant as the
piston to valve clearances were all checked *without* a gasket in place.
His continual waffling on this subject is nothing other than an exercise
in the ridiculous by a man who is out of his depth in understanding the subject matter, but here's the *really* stupid part.
In all his ramblings he has been doing nothing other than trying to find ways to blame me for the failure of this engine, and in doing so has
come up with an endless list of comical excuses as for why the engine
failed with each new one being more ridiculous than the last. His claims
of "valve lofting" or over revving" are utterly ridiculous, but even if
by some miracle they were accurate I have no idea how he could connect
me with them given that I wasn't driving the car :)
Moreover I have mentioned on a number of occasions that anything related
to the cylinder head also had nothing to do with me as the head was
machined and assembled by a third party. My job, such as it was, was to
make some modifications to the sump and oil puckup for ground clearance,
to assemble the engine using the parts supplied at the owner's
direction, and to set the valve clearances.
That was it. Whatever the cause of the fault, be it valve lofting
(lol :), over revving, broken valve spring, dropped collet, overly lean mixture or improper tune were all at the hands of someone else and had *nothing_to_do_with_me* :)
Fingers in the ear singing la la la la. Yeah, right. You do the job, you assume responsibility for the entire job.
Xeno wrote:
On 31/5/2026 3:34 pm, Axel wrote:
Xeno wrote:
On 29/5/2026 9:53 pm, Noddy wrote:
On 29/05/2026 6:01 pm, jonz wrote:
On 29-May-26 3:05 PM, jonz wrote:
-a-aThe 4A-GE(20), having a *5 valve per cylinder head*,
~~~~~~~~~~~~~~~~~would be actually creating valve loft to increase cylinder fill >>>>>>>>> at high RPM.
Nope, because of smaller/lighter valve size, the chances of
lofting in a 5 valve are reduced.... one of the reasons for a 5
valve design in the first place!.
This has been done to death, and the more this mental midget goes
on with this nonsense the more clueless he reveals himself to be.
The engine failed catastrophically on the turn in to the chase on
Conrod Straight at Mount Panarama on the 7th lap of a race. Prior
to that race the car had done various practice sessions, a full day >>>>> of test and tuning at another track (winton) and two separate full
dyno sessions without any hint of an issue.
Odd, Daryl clearly stated way back that it was running down conrod
straight when it blew. I have been mentioning conrod straight many
times and he has never questioned it. This looks to me like your
standard modus operandi of waiting a year or three and then, when
memories have faded, *alter the data* over to where you need it to
be. If Daryl had not made that point, I would never have arrived at
the valve lofting conclusion.-a >
The engine had *one* valve fail. It was *not* "creating valve loft to >>>>It only takes one. The next one might have been seconds away but
once that first one lets go, nothing more matters because the engine
is dead, dead, dead!
Next point, all high performance high revving engines rely on a
degree of lofting to gain those little bits of extra performance.
The benefits of valve lofting were discovered and utilised first in
the motorcycle racing industry when they first moved to OHV. It is
not deliberately used in today's OHC engines due to the lightweight
valve trains. Today's torque curves are achieved using precise
static valve lift profiles and variable valve timing rather than
relying on dynamic lofting. That said, a very high speed run down
conrod straight in a high gear at WOT is where you are most likely
to over rev the engine and see some unwanted lofting. This is a
point I made at the very beginning when Daryl first mention the
point at which the failure occurred.
increase cylinder fill" which is about as nonsensical a claim as
one can make. It failed because it stuck a valve in it's guide at
full lift
how does he know? could have been valve float
It failed because the head fell off due to piston contact and
subsequent overheating at the fillet, the hottest point of the
valve. Happens in moments when at WOT.
only if the valve is open during compression
Or if the valve got a light tap from the piston, enough so the valve
would no longer seat and seal during the compression and power
strokes. That would lead to a loss of valve head cooling, an instant
overheat due to burning>
which broke the valve off at the stem, punched it back up into the
head
Of course it would punch it up there. A loose valve head hasn't a
lot of room in a combustion chamber when the piston is moving at
15-30 Mps at high RPM and acting like the meanest hammer you would
ever see.
and forced the piston to rock in it's bore which immediately split
the bore and filled the cylinder with coolant.
must have been an aluminum block then
No, all the 4A-GE engines have cast iron blocks. The cylinder head is
alloy however - and it has 5 valves per cylinder.>
Irrelevant, that all happened post the initial cause.>
Daryl may still have the video of the thing when it failed where
the engine changed note and trailed a huge plume of white smoke out >>>>> of it's pipe. It was an instant component breakage which is not
unknown in the world of motorsport :)
Not when you take out piston to valve clearance and then create
valve lofting
valve lofting done properly won't cause piston to head contact, only
valve float or bounce does
Correct. *Done properly* are the operative words. The engine has to be
considered as a system and any single change will affect the system
and its related components. Therefore any change has to be sympathetic
to all aspects of the engine, not just one single aspect.>
through over revving because you (a) reduced clearance with a shim
head gasket
has he ever said he used a shim head gasket?
Yes, he did.
no, he just said he used the proper gasket
Nope. That's his invention. The engine used a Toyota competition
head gasket which is made specifically for this particular engine.
It's make to raise the compression by around half a point by being
thinner than a regular composite gasket. It is not a "shim", and
I've never used that
That was my point from the beginning. Engines typically have up to
0.100" piston to valve *static* clearance. Performance engines, like
the $A-GE(20), typically have a bit less but employ much more rigorous
*valve control*. Take some of that clearance, up to 0.020" in the case
of a shim head gasket, and the piston can hit the valve in extreme
circumstances - and flat out on conrod straight is an extreme
circumstance. When Daryl indicated the location of the blowup, the
cause became immediately apparent to me. Affect valve cooling in such
a circumstance and the valve head will overheat and drop off *in
seconds*. That, of course, will trigger a catastrophic failure, as
could be seen in the photos.
Darren claims he just fitted the head. I call bullshit on that. If I
were asked to do a job like that I would have pulled all the valves
and checked them out and I would have checked their sealing and
clearances.
unless you had full confidence in whoever did the head and knew what was done
I would have likely fitted lighter and stronger valves that were much
less likely to loft and/or bounce.
What Darren forgot was that removing head gasket thickness
automatically increases the compression ratio. That's done in order to
increase power and that power will come at increased revs. Therein
hangs the tale. >
and (b) didn't take counter measures, ie. lighter valves, stronger
springs, different cam profile. It happens to clowns like you all
the time.
Conrod straight is known for such failures because, quite simply, it
is possible to over rev the engine when running downhill, WOT, at
speed.
anyhow, since he only fitted the head as supplied, and used the correct gasket, the engine failure is hardly his fault
On 31/5/2026 7:51 pm, Noddy wrote:
On 31/05/2026 3:34 pm, Axel wrote:
Xeno wrote:
increase cylinder fill" which is about as nonsensical a claim as
one can make. It failed because it stuck a valve in it's guide at
full lift
how does he know? could have been valve float
It *wasn't* "valve float" Felix, and to make such a claim shows that you
You don't have a clue Darren. Your copout was calling it a faulty valve.
have no understanding of what it is or how it works.
Your conclusion - faulty valve - the standard copout from those
without a clue and one guaranteed to generate an encore!>
It failed because the head fell off due to piston contact and
subsequent overheating at the fillet, the hottest point of the
valve. Happens in moments when at WOT.
only if the valve is open during compression
Nope. As I said, it was a valve as full lift striking the piston which
A 4A-GE valve at full lift cannot strike the piston.
That's what the piston cutouts are for.
caused the engine failure. That much is obvious to anyone with an
ounce of experience (which would *not* be your mental mate). The only
point of conjecture is why the valve was *at* full lift when the
piston hit it, and there are a few reasons for that. It could have
broken a valve spring, it could have dropped a collet, and it could
have had a tight guide that saw the valve "grab". What it most
definitely was *not* was a result of "loft" or a mechanical piston to
valve clearance issue.
Again Darren, you have shown yourself to be truly clueless, impeccably
so! The 4A-GE series are *NOT* interference engines. A valve at full
lift (normal) *cannot* contact the piston. The only way the piston
could ever contact a valve head is if the valve had *extended travel*,
as in when valve float or lofting occurs.>
I have shown these pictures before Felix, but as usual you have the
retention ability of a dead goldfish. This is the type of valve
failure you get from a minor piston to valve clearance issue, and
it's commonly seen whenever an interference type engine breaks a
timing belt:
See above, you can break the belt on a 4A-GE and the valves will not
hit pistons. The only way a 4A-GE valve can hit a piston is if it's
travel gets extended beyond what the cam will lift it. (Read: float, lofting, overshoot)>
https://ibb.co/mcKy0q5
As can be seen, the valves in this picture are not bent severely, but
certainly bent enough to cause an instant loss of compression
resulting in a dead cylinder. That's *not* what happened in this case.
This is what happened:
https://ibb.co/cwxR1yL
That valve came away at the fillet, the hottest point of the valve and
it can be clearly seen in your pic. That's where I would expect it to
break given the circumstances I outlined and indeed that's where it
did break. You really don't understand this stuff very much, do you? >
You can't see it clearly in this pic, but the valve had been snapped
off half way up it's stem and then hammered back up into it's port
pocket. It was an instant catastrophic failure that was a result of a
component breakage, and it gave zero warning before it occurred.
Standard behaviour and what one could reasonably expect. Understand
that, once the valve no longer seats properly, head temperature will
rapidly rise until the fillet area becomes plastic. At that point the
head will detach and the whole process to that point is mere seconds
at WOT. Once that head is detached, then you are in the realm of catastrophic failure and a valve head being wedged into the port or
wedged into a *new slot* in the *piston* is the usual outcome. If the
valve head cant find a space to hide - the port - it will make a space
to hide - in the piston. That's why this type of failure is commonly
known as *penny in the slot*. >
Despite the nonsensical claims of your mental mate, this is *not*
what happens if a valve has been bent slightly from a piston to valve
clearance issue, as any kind of bent valve will cause an instant
compression loss which will be apparent to the driver. And I can tell
you that had such a compression loss occurred Les would have shut the
car down and got it into the pits to investigate :)
It only needs a slight compression loss from a slight bend and, at
high RPM, there will be more than enough compression to create a very
hot burn and, due to the poor valve seating, that burn will be
blasting through the valve seat further exacerbating the valve head
overheat situation.>
and forced the piston to rock in it's bore which immediately split
the bore and filled the cylinder with coolant.
must have been an aluminum block then
Wrong again Felix. Cast iron block, and split bores in cast iron
blocks are not that uncommon. It's very easy to do with you have a
piston and valve remains fighting for an area that is not big enough
to accommodate them.
For once you are correct. I must say, it was patently obvious.>
I used to split bores on Chev V8 engines from running 40lbs of boost
thought a supercharger :)
Photos or it's more bullshit from you. Oh, and not just you as a
*spectator* at the track.>
Not when you take out piston to valve clearance and then create
valve lofting
valve lofting done properly won't cause piston to head contact, only
valve float or bounce does
Refers to the same thing. Valve *lofting* is when the float is
designed in whereas valve float is an undesired effect at high RPM.
The old grey motor Holdens were well known for it and it got
destructive if allowed to continue. With valve lofting, on the other
hand, the landing zone on the cam lobe is *curated* so there's no
extreme hammering effects.
Correct. This is a perfect example of your clueless mental mate
trying to pass off technical terms he doesn't understand as
explanations for faults he has no idea about.
through over revving because you (a) reduced clearance with a shim
head gasket
has he ever said he used a shim head gasket?
Nope. That's his invention. The engine used a Toyota competition head
gasket which is made specifically for this particular engine. It's
make to raise the compression by around half a point by being thinner
than a regular composite gasket. It is not a "shim", and I've never
used that
Same effect. It is *thinner*. That was my point.
term. That's something he made up. Either way, it's irrelevant as the
piston to valve clearances were all checked *without* a gasket in place.
Nope, not something I made up. Making shit up is your bag. Shim head
gaskets have been known in the trade for as long as I can recall.
https://northernautoparts.com/blog/vintage-chevy-shim-head-gaskets/
For the record, shim head gaskets can be used to restore compression
ratios after head and/or deck machining so it's not a new term by any
means and definitely not a new concept. About that apprenticeship in
auto machining that you claim to have done - I call bullshit - you
don't know stuff of which I would reasonably expect someone in that
industry in particular to be 100% cogniscant.
His continual waffling on this subject is nothing other than an
exercise in the ridiculous by a man who is out of his depth in
understanding the subject matter, but here's the *really* stupid part.
Darren, the only one floundering here is you! Here, take this straw!>
In all his ramblings he has been doing nothing other than trying to
find ways to blame me for the failure of this engine, and in doing so
has
Pardon? Weren't you working on the engine? I am only directing blame
where the responsibility lies!
come up with an endless list of comical excuses as for why the engine
failed with each new one being more ridiculous than the last. His claims
Same concept all the way through, I have made no change.
of "valve lofting" or over revving" are utterly ridiculous, but even
if by some miracle they were accurate I have no idea how he could
connect me with them given that I wasn't driving the car :)
Nope, always I have been on the same path. I said over revving from
the very beginning, I said lofting, float and bounce from the
beginning, might have mentioned overshoot too - same concept.>
Moreover I have mentioned on a number of occasions that anything
related to the cylinder head also had nothing to do with me as the
head was machined and assembled by a third party. My job, such as it
was, was to
You make a mod, you assemble, you *assume responsibility*, that's how
it works. When you are presented with a completely assembled head, and
you want to make mods to the engine on assembly, it behooves you to
check what others have done before you - even if that means some
dismantling - and it definitely means you will check such things as
seat sealing and valve springs and collets. As I said, you assemble,
you assume responsibility. You modify, you 100% assume responsibility.
make some modifications to the sump and oil puckup for ground
clearance, to assemble the engine using the parts supplied at the
owner's direction, and to set the valve clearances.
You claim motor mechanic qualifications therefore the customer can
assume you have the technical knowhow. Obviouly Les didn't know what
an inveterate liar you are so, in his assumption that you were honest
*AND QUALIFIED*, he made an ASS out of himself.-a >
That was it. Whatever the cause of the fault, be it valve loftingassume responsibility for the entire job.
(lol :), over revving, broken valve spring, dropped collet, overly
lean mixture or improper tune were all at the hands of someone else
and had *nothing_to_do_with_me* :)
Fingers in the ear singing la la la la. Yeah, right. You do the job, you
Never ASSUME since you will make an ASS out of YOU and ME. Well,
you're not making an ass out of me Darren, your job, your screwup. The
worst part, you can't even backtrack to find the root cause so you
will repeat such mistakes over and over. You don't know how lucky the
world is when you decided to *retire* and do only your own work. Now
you'll be able to easily hide your next cockups. And there will be
cockups, rest assured of that!
On 1/6/2026 10:51 am, Axel wrote:
Xeno wrote:
On 31/5/2026 3:34 pm, Axel wrote:
Xeno wrote:
On 29/5/2026 9:53 pm, Noddy wrote:
On 29/05/2026 6:01 pm, jonz wrote:
On 29-May-26 3:05 PM, jonz wrote:
-a-aThe 4A-GE(20), having a *5 valve per cylinder head*,
~~~~~~~~~~~~~~~~~would be actually creating valve loft to increase cylinder >>>>>>>>>> fill at high RPM.
Nope, because of smaller/lighter valve size, the chances of
lofting in a 5 valve are reduced.... one of the reasons for a 5 >>>>>>> valve design in the first place!.
This has been done to death, and the more this mental midget goes >>>>>> on with this nonsense the more clueless he reveals himself to be.
The engine failed catastrophically on the turn in to the chase on >>>>>> Conrod Straight at Mount Panarama on the 7th lap of a race. Prior >>>>>> to that race the car had done various practice sessions, a full
day of test and tuning at another track (winton) and two separate >>>>>> full dyno sessions without any hint of an issue.
Odd, Daryl clearly stated way back that it was running down conrod
straight when it blew. I have been mentioning conrod straight many
times and he has never questioned it. This looks to me like your
standard modus operandi of waiting a year or three and then, when
memories have faded, *alter the data* over to where you need it to
be. If Daryl had not made that point, I would never have arrived
at the valve lofting conclusion.-a >
The engine had *one* valve fail. It was *not* "creating valve
loft to
It only takes one. The next one might have been seconds away but
once that first one lets go, nothing more matters because the
engine is dead, dead, dead!
Next point, all high performance high revving engines rely on a
degree of lofting to gain those little bits of extra performance.
The benefits of valve lofting were discovered and utilised first
in the motorcycle racing industry when they first moved to OHV. It
is not deliberately used in today's OHC engines due to the
lightweight valve trains. Today's torque curves are achieved using
precise static valve lift profiles and variable valve timing
rather than relying on dynamic lofting. That said, a very high
speed run down conrod straight in a high gear at WOT is where you
are most likely to over rev the engine and see some unwanted
lofting. This is a point I made at the very beginning when Daryl
first mention the point at which the failure occurred.
increase cylinder fill" which is about as nonsensical a claim as
one can make. It failed because it stuck a valve in it's guide at >>>>>> full lift
how does he know? could have been valve float
It failed because the head fell off due to piston contact and
subsequent overheating at the fillet, the hottest point of the
valve. Happens in moments when at WOT.
only if the valve is open during compression
Or if the valve got a light tap from the piston, enough so the valve
would no longer seat and seal during the compression and power
strokes. That would lead to a loss of valve head cooling, an instant
overheat due to burning>
which broke the valve off at the stem, punched it back up into
the head
Of course it would punch it up there. A loose valve head hasn't a
lot of room in a combustion chamber when the piston is moving at
15-30 Mps at high RPM and acting like the meanest hammer you would
ever see.
and forced the piston to rock in it's bore which immediately
split the bore and filled the cylinder with coolant.
must have been an aluminum block then
No, all the 4A-GE engines have cast iron blocks. The cylinder head
is alloy however - and it has 5 valves per cylinder.>
Irrelevant, that all happened post the initial cause.>
Daryl may still have the video of the thing when it failed where
the engine changed note and trailed a huge plume of white smoke
out of it's pipe. It was an instant component breakage which is
not unknown in the world of motorsport :)
Not when you take out piston to valve clearance and then create
valve lofting
valve lofting done properly won't cause piston to head contact,
only valve float or bounce does
Correct. *Done properly* are the operative words. The engine has to
be considered as a system and any single change will affect the
system and its related components. Therefore any change has to be
sympathetic to all aspects of the engine, not just one single aspect.> >>>>> through over revving because you (a) reduced clearance with a shim
head gasket
has he ever said he used a shim head gasket?
Yes, he did.
no, he just said he used the proper gasket
No, he used a thinner gasket than standard.
His words;
Nope. That's his invention. The engine used a Toyota competition
head gasket which is made specifically for this particular engine.
It's make to raise the compression by around half a point by being
thinner than a regular composite gasket. It is not a "shim", and
I've never used that
It is thinner than standard so the general term is a *shim head gasket*.>
That was my point from the beginning. Engines typically have up to
0.100" piston to valve *static* clearance. Performance engines, like
the $A-GE(20), typically have a bit less but employ much more
rigorous *valve control*. Take some of that clearance, up to 0.020"
in the case of a shim head gasket, and the piston can hit the valve
in extreme circumstances - and flat out on conrod straight is an
extreme circumstance. When Daryl indicated the location of the
blowup, the cause became immediately apparent to me. Affect valve
cooling in such a circumstance and the valve head will overheat and
drop off *in seconds*. That, of course, will trigger a catastrophic
failure, as could be seen in the photos.
Darren claims he just fitted the head. I call bullshit on that. If I
were asked to do a job like that I would have pulled all the valves
and checked them out and I would have checked their sealing and
clearances.
unless you had full confidence in whoever did the head and knew what
was done
He didn't even know who that person was.>
He used a thinner head gasket than standard, he even says that in hisI would have likely fitted lighter and stronger valves that were
much less likely to loft and/or bounce.
What Darren forgot was that removing head gasket thickness
automatically increases the compression ratio. That's done in order
to increase power and that power will come at increased revs.
Therein hangs the tale. >
and (b) didn't take counter measures, ie. lighter valves, stronger
springs, different cam profile. It happens to clowns like you all
the time.
Conrod straight is known for such failures because, quite simply,
it is possible to over rev the engine when running downhill, WOT,
at speed.
anyhow, since he only fitted the head as supplied, and used the
correct gasket, the engine failure is hardly his fault
recent bullshit. https://northernautoparts.com/blog/vintage-chevy-shim-head-gaskets/
A thinner head gasket than standard is called a *shim head gasket*.
It's a term I have known and used since my apprenticeship days.
See my recent post on taking responsibility of a job.
Xeno wrote:
On 31/5/2026 7:51 pm, Noddy wrote:
On 31/05/2026 3:34 pm, Axel wrote:You don't have a clue Darren. Your copout was calling it a faulty valve.
Xeno wrote:
increase cylinder fill" which is about as nonsensical a claim as
one can make. It failed because it stuck a valve in it's guide at >>>>>> full lift
how does he know? could have been valve float
It *wasn't* "valve float" Felix, and to make such a claim shows that you >>
have no understanding of what it is or how it works.
Your conclusion - faulty valve - the standard copout from those
without a clue and one guaranteed to generate an encore!>
It failed because the head fell off due to piston contact and
subsequent overheating at the fillet, the hottest point of the
valve. Happens in moments when at WOT.
only if the valve is open during compression
Nope. As I said, it was a valve as full lift striking the piston which
A 4A-GE valve at full lift cannot strike the piston.
I would think so. full lift would be a normal position for it. it would
have to go beyond full lift. ie, bounce
That's what the piston cutouts are for.
caused the engine failure. That much is obvious to anyone with an
ounce of experience (which would *not* be your mental mate). The only
point of conjecture is why the valve was *at* full lift when the
piston hit it, and there are a few reasons for that. It could have
broken a valve spring, it could have dropped a collet, and it could
have had a tight guide that saw the valve "grab". What it most
definitely was *not* was a result of "loft" or a mechanical piston to
valve clearance issue.
Again Darren, you have shown yourself to be truly clueless, impeccably
so! The 4A-GE series are *NOT* interference engines. A valve at full
lift (normal) *cannot* contact the piston. The only way the piston
could ever contact a valve head is if the valve had *extended travel*,
as in when valve float or lofting occurs.>
that's my understanding
I have shown these pictures before Felix, but as usual you have the
retention ability of a dead goldfish. This is the type of valve
failure you get from a minor piston to valve clearance issue, and
it's commonly seen whenever an interference type engine breaks a
timing belt:
See above, you can break the belt on a 4A-GE and the valves will not
hit pistons. The only way a 4A-GE valve can hit a piston is if it's
travel gets extended beyond what the cam will lift it. (Read: float,
lofting, overshoot)>
as per my comment above
https://ibb.co/mcKy0q5
As can be seen, the valves in this picture are not bent severely, but
certainly bent enough to cause an instant loss of compression
resulting in a dead cylinder. That's *not* what happened in this case.
This is what happened:
https://ibb.co/cwxR1yL
That valve came away at the fillet, the hottest point of the valve and
it can be clearly seen in your pic. That's where I would expect it to
break given the circumstances I outlined and indeed that's where it
did break. You really don't understand this stuff very much, do you? >
You can't see it clearly in this pic, but the valve had been snapped
off half way up it's stem and then hammered back up into it's port
pocket. It was an instant catastrophic failure that was a result of a
component breakage, and it gave zero warning before it occurred.
Standard behaviour and what one could reasonably expect. Understand
that, once the valve no longer seats properly, head temperature will
rapidly rise until the fillet area becomes plastic. At that point the
head will detach and the whole process to that point is mere seconds
at WOT. Once that head is detached, then you are in the realm of
catastrophic failure and a valve head being wedged into the port or
wedged into a *new slot* in the *piston* is the usual outcome. If the
valve head cant find a space to hide - the port - it will make a space
to hide - in the piston. That's why this type of failure is commonly
known as *penny in the slot*. >
Despite the nonsensical claims of your mental mate, this is *not*
what happens if a valve has been bent slightly from a piston to valve
clearance issue, as any kind of bent valve will cause an instant
compression loss which will be apparent to the driver. And I can tell
you that had such a compression loss occurred Les would have shut the
car down and got it into the pits to investigate :)
It only needs a slight compression loss from a slight bend and, at
high RPM, there will be more than enough compression to create a very
hot burn and, due to the poor valve seating, that burn will be
blasting through the valve seat further exacerbating the valve head
overheat situation.>
and forced the piston to rock in it's bore which immediately split >>>>>> the bore and filled the cylinder with coolant.
must have been an aluminum block then
Wrong again Felix. Cast iron block, and split bores in cast iron
blocks are not that uncommon. It's very easy to do with you have a
piston and valve remains fighting for an area that is not big enough
to accommodate them.
For once you are correct. I must say, it was patently obvious.>
I used to split bores on Chev V8 engines from running 40lbs of boost
thought a supercharger :)
Photos or it's more bullshit from you. Oh, and not just you as a
*spectator* at the track.>
Not when you take out piston to valve clearance and then create
valve lofting
valve lofting done properly won't cause piston to head contact, only
valve float or bounce does
Refers to the same thing. Valve *lofting* is when the float is
designed in whereas valve float is an undesired effect at high RPM.
yes so not the same thing
The old grey motor Holdens were well known for it and it got
destructive if allowed to continue. With valve lofting, on the other
hand, the landing zone on the cam lobe is *curated* so there's no
extreme hammering effects.
Correct. This is a perfect example of your clueless mental mate
trying to pass off technical terms he doesn't understand as
explanations for faults he has no idea about.
through over revving because you (a) reduced clearance with a shim
head gasket
has he ever said he used a shim head gasket?
Nope. That's his invention. The engine used a Toyota competition head
gasket which is made specifically for this particular engine. It's
make to raise the compression by around half a point by being thinner
than a regular composite gasket. It is not a "shim", and I've never
used that
Same effect. It is *thinner*. That was my point.
but the gasket was made for that engine?
term. That's something he made up. Either way, it's irrelevant as the
piston to valve clearances were all checked *without* a gasket in place.
Nope, not something I made up. Making shit up is your bag. Shim head
gaskets have been known in the trade for as long as I can recall.
https://northernautoparts.com/blog/vintage-chevy-shim-head-gaskets/
For the record, shim head gaskets can be used to restore compression
ratios after head and/or deck machining so it's not a new term by any
means and definitely not a new concept. About that apprenticeship in
auto machining that you claim to have done - I call bullshit - you
don't know stuff of which I would reasonably expect someone in that
industry in particular to be 100% cogniscant.
His continual waffling on this subject is nothing other than an
exercise in the ridiculous by a man who is out of his depth in
understanding the subject matter, but here's the *really* stupid part.
Darren, the only one floundering here is you! Here, take this straw!>
In all his ramblings he has been doing nothing other than trying to
find ways to blame me for the failure of this engine, and in doing so
has
Pardon? Weren't you working on the engine? I am only directing blame
where the responsibility lies!
come up with an endless list of comical excuses as for why the engineSame concept all the way through, I have made no change.
failed with each new one being more ridiculous than the last. His claims >>
of "valve lofting" or over revving" are utterly ridiculous, but even
if by some miracle they were accurate I have no idea how he could
connect me with them given that I wasn't driving the car :)
Nope, always I have been on the same path. I said over revving from
the very beginning, I said lofting, float and bounce from the
beginning, might have mentioned overshoot too - same concept.>
Moreover I have mentioned on a number of occasions that anything
related to the cylinder head also had nothing to do with me as the
head was machined and assembled by a third party. My job, such as it
was, was to
You make a mod, you assemble, you *assume responsibility*, that's how
it works. When you are presented with a completely assembled head, and
you want to make mods to the engine on assembly, it behooves you to
check what others have done before you - even if that means some
dismantling - and it definitely means you will check such things as
seat sealing and valve springs and collets. As I said, you assemble,
you assume responsibility. You modify, you 100% assume responsibility.
make some modifications to the sump and oil puckup for ground
clearance, to assemble the engine using the parts supplied at the
owner's direction, and to set the valve clearances.
You claim motor mechanic qualifications therefore the customer can
assume you have the technical knowhow. Obviouly Les didn't know what
an inveterate liar you are so, in his assumption that you were honest
*AND QUALIFIED*, he made an ASS out of himself.-a >
That was it. Whatever the cause of the fault, be it valve lofting
(lol :), over revving, broken valve spring, dropped collet, overly
lean mixture or improper tune were all at the hands of someone else
and had *nothing_to_do_with_me* :)
Fingers in the ear singing la la la la. Yeah, right. You do the job, you >> assume responsibility for the entire job.
Never ASSUME since you will make an ASS out of YOU and ME. Well,
you're not making an ass out of me Darren, your job, your screwup. The
worst part, you can't even backtrack to find the root cause so you
will repeat such mistakes over and over. You don't know how lucky the
world is when you decided to *retire* and do only your own work. Now
you'll be able to easily hide your next cockups. And there will be
cockups, rest assured of that!
Xeno wrote:
On 1/6/2026 10:51 am, Axel wrote:
Xeno wrote:
On 31/5/2026 3:34 pm, Axel wrote:
Xeno wrote:
On 29/5/2026 9:53 pm, Noddy wrote:
On 29/05/2026 6:01 pm, jonz wrote:
On 29-May-26 3:05 PM, jonz wrote:
-a-aThe 4A-GE(20), having a *5 valve per cylinder head*,
~~~~~~~~~~~~~~~~~would be actually creating valve loft to increase cylinder >>>>>>>>>>> fill at high RPM.
Nope, because of smaller/lighter valve size, the chances of
lofting in a 5 valve are reduced.... one of the reasons for a 5 >>>>>>>> valve design in the first place!.
This has been done to death, and the more this mental midget goes >>>>>>> on with this nonsense the more clueless he reveals himself to be. >>>>>>>
The engine failed catastrophically on the turn in to the chase on >>>>>>> Conrod Straight at Mount Panarama on the 7th lap of a race. Prior >>>>>>> to that race the car had done various practice sessions, a full >>>>>>> day of test and tuning at another track (winton) and two separate >>>>>>> full dyno sessions without any hint of an issue.
Odd, Daryl clearly stated way back that it was running down conrod >>>>>> straight when it blew. I have been mentioning conrod straight many >>>>>> times and he has never questioned it. This looks to me like your
standard modus operandi of waiting a year or three and then, when >>>>>> memories have faded, *alter the data* over to where you need it to >>>>>> be. If Daryl had not made that point, I would never have arrived
at the valve lofting conclusion.-a >
The engine had *one* valve fail. It was *not* "creating valve
loft to
It only takes one. The next one might have been seconds away but
once that first one lets go, nothing more matters because the
engine is dead, dead, dead!
Next point, all high performance high revving engines rely on a
degree of lofting to gain those little bits of extra performance. >>>>>> The benefits of valve lofting were discovered and utilised first
in the motorcycle racing industry when they first moved to OHV. It >>>>>> is not deliberately used in today's OHC engines due to the
lightweight valve trains. Today's torque curves are achieved using >>>>>> precise static valve lift profiles and variable valve timing
rather than relying on dynamic lofting. That said, a very high
speed run down conrod straight in a high gear at WOT is where you >>>>>> are most likely to over rev the engine and see some unwanted
lofting. This is a point I made at the very beginning when Daryl
first mention the point at which the failure occurred.
increase cylinder fill" which is about as nonsensical a claim as >>>>>>> one can make. It failed because it stuck a valve in it's guide at >>>>>>> full lift
how does he know? could have been valve float
It failed because the head fell off due to piston contact and
subsequent overheating at the fillet, the hottest point of the
valve. Happens in moments when at WOT.
only if the valve is open during compression
Or if the valve got a light tap from the piston, enough so the valve
would no longer seat and seal during the compression and power
strokes. That would lead to a loss of valve head cooling, an instant
overheat due to burning>
which broke the valve off at the stem, punched it back up into
the head
Of course it would punch it up there. A loose valve head hasn't a >>>>>> lot of room in a combustion chamber when the piston is moving at
15-30 Mps at high RPM and acting like the meanest hammer you would >>>>>> ever see.
and forced the piston to rock in it's bore which immediately
split the bore and filled the cylinder with coolant.
must have been an aluminum block then
No, all the 4A-GE engines have cast iron blocks. The cylinder head
is alloy however - and it has 5 valves per cylinder.>
Irrelevant, that all happened post the initial cause.>
Daryl may still have the video of the thing when it failed where >>>>>>> the engine changed note and trailed a huge plume of white smoke >>>>>>> out of it's pipe. It was an instant component breakage which is >>>>>>> not unknown in the world of motorsport :)
Not when you take out piston to valve clearance and then create
valve lofting
valve lofting done properly won't cause piston to head contact,
only valve float or bounce does
Correct. *Done properly* are the operative words. The engine has to
be considered as a system and any single change will affect the
system and its related components. Therefore any change has to be
sympathetic to all aspects of the engine, not just one single aspect.> >>>>>> through over revving because you (a) reduced clearance with a shim >>>>>> head gasket
has he ever said he used a shim head gasket?
Yes, he did.
no, he just said he used the proper gasket
No, he used a thinner gasket than standard.
His words;
Nope. That's his invention. The engine used a Toyota competition
head gasket which is made specifically for this particular engine.
It's make to raise the compression by around half a point by being
thinner than a regular composite gasket. It is not a "shim", and
I've never used that
It is thinner than standard so the general term is a *shim head gasket*.> >>>> That was my point from the beginning. Engines typically have up to
0.100" piston to valve *static* clearance. Performance engines, like
the $A-GE(20), typically have a bit less but employ much more
rigorous *valve control*. Take some of that clearance, up to 0.020"
in the case of a shim head gasket, and the piston can hit the valve
in extreme circumstances - and flat out on conrod straight is an
extreme circumstance. When Daryl indicated the location of the
blowup, the cause became immediately apparent to me. Affect valve
cooling in such a circumstance and the valve head will overheat and
drop off *in seconds*. That, of course, will trigger a catastrophic
failure, as could be seen in the photos.
Darren claims he just fitted the head. I call bullshit on that. If I
were asked to do a job like that I would have pulled all the valves
and checked them out and I would have checked their sealing and
clearances.
unless you had full confidence in whoever did the head and knew what
was done
He didn't even know who that person was.>
He used a thinner head gasket than standard, he even says that in hisI would have likely fitted lighter and stronger valves that were
much less likely to loft and/or bounce.
What Darren forgot was that removing head gasket thickness
automatically increases the compression ratio. That's done in order
to increase power and that power will come at increased revs.
Therein hangs the tale. >
and (b) didn't take counter measures, ie. lighter valves, stronger >>>>>> springs, different cam profile. It happens to clowns like you all >>>>>> the time.
Conrod straight is known for such failures because, quite simply, >>>>>> it is possible to over rev the engine when running downhill, WOT, >>>>>> at speed.
anyhow, since he only fitted the head as supplied, and used the
correct gasket, the engine failure is hardly his fault
recent bullshit.
https://northernautoparts.com/blog/vintage-chevy-shim-head-gaskets/
A thinner head gasket than standard is called a *shim head gasket*.
It's a term I have known and used since my apprenticeship days.
See my recent post on taking responsibility of a job.
but he also said he checked the valve clearances without the gasket in
place
On 1/06/2026 10:51 am, Axel wrote:
Xeno wrote:
has he ever said he used a shim head gasket?
Yes, he did.
no, he just said he used the proper gasket
That's right Felix. The gasket used was Toyota competition head gasket
made specifically for that engine. As I mentioned, I have never claimed
to have used a "shim" head gasket, and for the specific reason being
that such a term isn't in my vocabulary. There is no such thing as a
"shim head gasket". There are only head gasket shims, and head gaskets.
You cannot run a head gasket shim on it's own, and they are not designed
to seal.
As you can see here, regardless of being told the facts of the matter,
and more than once I might add, he *still* persists in ignoring reality
and inserting his own bullshit.
This is the moron you're trying to argue sense with.
That was my point from the beginning. Engines typically have up to
0.100" piston to valve *static* clearance. Performance engines, like
the $A-GE(20), typically have a bit less but employ much more
rigorous *valve control*. Take some of that clearance, up to 0.020"
in the case of a shim head gasket, and the piston can hit the valve
in extreme circumstances - and flat out on conrod straight is an
extreme circumstance. When Daryl indicated the location of the
blowup, the cause became immediately apparent to me. Affect valve
cooling in such a circumstance and the valve head will overheat and
drop off *in seconds*. That, of course, will trigger a catastrophic
failure, as could be seen in the photos.
Darren claims he just fitted the head. I call bullshit on that. If I
were asked to do a job like that I would have pulled all the valves
and checked them out and I would have checked their sealing and
clearances.
unless you had full confidence in whoever did the head and knew what
was done
As mentioned, the head was delivered to my place fully assembled having
been done by other people, and any fault the head may or may not have
had is between the owner and the head people to argue over. It's not my
job to check *other* people's work.
This bloke is living ion fantasy land. He would never have done a job
like this because (a) it's out of his depth which is abundantly clear
from his moronic comments, and (b) if he was dismantling and checking
every single component that he had nothing to do with he'd spend an *extraordinary* amount of time not getting paid :)
I remember him making a similar nonsensical outburst some years ago when
I mentioned that the bloke next door had blown the diff in his 105
series Land Cruiser and I was fitting a used diff centre to it. He made
a *huge* song and dance about how "a real mechanic would rebuild the original diff", while having zero appreciation of the fact that all the owner was interested in paying for was the cheapest way to get the car
back on the road.
The funniest part was when he claimed that in the past he would have
ignored customer requests and told them to fuck off if they didn't want
to do what he recommended, and it was interesting to note that he had no answer to the question of when he was ever in a position to deal
directly with customers.
Such is the level of delusion :)
I would have likely fitted lighter and stronger valves that were much
less likely to loft and/or bounce.
What Darren forgot was that removing head gasket thickness
automatically increases the compression ratio. That's done in order
to increase power and that power will come at increased revs. Therein
hangs the tale. >
anyhow, since he only fitted the head as supplied, and used the
correct gasket, the engine failure is hardly his fault
He's been told this *many* times Felix, but his inferiority complex
prevents him from accepting that. Instead, he'll keep inventing utterly ridiculous excuses to try to lay the blame at my feet while achieving nothing other than making *himself* look completely clueless in the
process.
Such is the state of his mind.
Again Darren, you have shown yourself to be truly clueless, impeccably
so! The 4A-GE series are *NOT* interference engines. A valve at full
lift (normal) *cannot* contact the piston. The only way the piston could ever contact a valve head is if the valve had *extended travel*, as in
when valve float or lofting occurs.>
On 1/06/2026 3:12 pm, Xeno wrote:
Again Darren, you have shown yourself to be truly clueless, impeccably
so! The 4A-GE series are *NOT* interference engines. A valve at full
lift (normal) *cannot* contact the piston. The only way the piston
could ever contact a valve head is if the valve had *extended travel*,
as in when valve float or lofting occurs.>
According to your favourite source of information - AI
Whether the Toyota 4AGE 20-valve is an interference engine depends on
which specific version you have:Silvertop (Early 20v): This version is a non-interference engine. If the timing belt snaps, the valves and
pistons will not collide.Blacktop (Late 20v): This version is an interference engine. If the timing belt fails, the valves and pistons
will collide, causing significant internal damage.Because 4AGE blocks
and heads are highly interchangeable, many modified engines blur these lines. For example, putting Blacktop pistons into a Silvertop block
converts it into an interference setup.
A 4A-GE valve at full lift cannot strike the piston.
I would think so. full lift would be a normal position for it. it
would have to go beyond full lift. ie, bounce
Again Darren, you have shown yourself to be truly clueless,
impeccably so! The 4A-GE series are *NOT* interference engines. A
valve at full lift (normal) *cannot* contact the piston. The only
way the piston could ever contact a valve head is if the valve had
*extended travel*, as in when valve float or lofting occurs.>
that's my understanding
See above, you can break the belt on a 4A-GE and the valves will
not hit pistons. The only way a 4A-GE valve can hit a piston is if
it's travel gets extended beyond what the cam will lift it. (Read:
float, lofting, overshoot)>
as per my comment above
AI Overview
Yes, the Toyota 4A-GE 20-valve "Blacktop" engine is an interference engine.If the timing belt snaps or jumps teeth,
the valves will collide with the pistons, leading to severe and costly internal damage.
Here are a few quick facts about the Blacktop's valvetrain:
The Cause of the Interference: The Blacktop has higher-lift camshafts and flatter pistons (with only 2 valve reliefs) to achieve a higher compression ratio (11.0:1). This means the valves dip into the piston's travel path when fully open.
The "Silvertop" Difference: Interestingly, its predecessor, the 20-valve "Silvertop," is a non-interference engine. It uses pistons with deeper, 5-valve reliefs, giving the valves enough clearance to avoid hitting the pistons if the timing belt breaks.
Refers to the same thing. Valve *lofting* is when the float is
designed in whereas valve float is an undesired effect at high
RPM.
yes so not the same thing
Nope. That's his invention. The engine used a Toyota competition
head gasket which is made specifically for this particular
engine. It's make to raise the compression by around half a
point by being thinner than a regular composite gasket. It is
not a "shim", and I've never used that
Same effect. It is *thinner*. That was my point.
but the gasket was made for that engine?
Xeno wrote:
See my recent post on taking responsibility of a job.
but he also said he checked the valve clearances without the gasket in
place
Noddy wrote:
This is the moron you're trying to argue sense with.
at least I can have a sensible civil discussion with him, unlike with you
https://carfromjapan.com/wp-content/uploads/2023/09/burnt-exhaust-valve-symptoms-1024x683.jpg
On 1/06/2026 3:12 pm, Xeno wrote:
Again Darren, you have shown yourself to be truly clueless, impeccably
so! The 4A-GE series are *NOT* interference engines. A valve at full
lift (normal) *cannot* contact the piston. The only way the piston
could ever contact a valve head is if the valve had *extended travel*,
as in when valve float or lofting occurs.>
According to your favourite source of information - AI
Whether the Toyota 4AGE 20-valve is an interference engine depends on
which specific version you have:Silvertop (Early 20v): This version is a non-interference engine. If the timing belt snaps, the valves and
pistons will not collide.Blacktop (Late 20v): This version is an interference engine. If the timing belt fails, the valves and pistons
will collide, causing significant internal damage.Because 4AGE blocks
and heads are highly interchangeable, many modified engines blur these lines. For example, putting Blacktop pistons into a Silvertop block
converts it into an interference setup.
On 1/6/2026 3:51 pm, Axel wrote:
Xeno wrote:
On 31/5/2026 7:51 pm, Noddy wrote:
On 31/05/2026 3:34 pm, Axel wrote:
Xeno wrote:
increase cylinder fill" which is about as nonsensical a claim as >>>>>>> one can make. It failed because it stuck a valve in it's guide
at full lift
how does he know? could have been valve float
It *wasn't* "valve float" Felix, and to make such a claim shows
that you
You don't have a clue Darren. Your copout was calling it a faulty
valve.
have no understanding of what it is or how it works.
Your conclusion - faulty valve - the standard copout from those
without a clue and one guaranteed to generate an encore!>
A 4A-GE valve at full lift cannot strike the piston.It failed because the head fell off due to piston contact and
subsequent overheating at the fillet, the hottest point of the
valve. Happens in moments when at WOT.
only if the valve is open during compression
Nope. As I said, it was a valve as full lift striking the piston which >>>
I would think so. full lift would be a normal position for it. it
would have to go beyond full lift. ie, bounce
That's what the piston cutouts are for.
caused the engine failure. That much is obvious to anyone with an
ounce of experience (which would *not* be your mental mate). The
only point of conjecture is why the valve was *at* full lift when
the piston hit it, and there are a few reasons for that. It could
have broken a valve spring, it could have dropped a collet, and it
could have had a tight guide that saw the valve "grab". What it
most definitely was *not* was a result of "loft" or a mechanical
piston to valve clearance issue.
Again Darren, you have shown yourself to be truly clueless,
impeccably so! The 4A-GE series are *NOT* interference engines. A
valve at full lift (normal) *cannot* contact the piston. The only
way the piston could ever contact a valve head is if the valve had
*extended travel*, as in when valve float or lofting occurs.>
that's my understanding
I have shown these pictures before Felix, but as usual you have the
retention ability of a dead goldfish. This is the type of valve
failure you get from a minor piston to valve clearance issue, and
it's commonly seen whenever an interference type engine breaks a
timing belt:
See above, you can break the belt on a 4A-GE and the valves will not
hit pistons. The only way a 4A-GE valve can hit a piston is if it's
travel gets extended beyond what the cam will lift it. (Read: float,
lofting, overshoot)>
as per my comment above
https://ibb.co/mcKy0q5
As can be seen, the valves in this picture are not bent severely,
but certainly bent enough to cause an instant loss of compression
resulting in a dead cylinder. That's *not* what happened in this case. >>>>
This is what happened:
https://ibb.co/cwxR1yL
That valve came away at the fillet, the hottest point of the valve
and it can be clearly seen in your pic. That's where I would expect
it to break given the circumstances I outlined and indeed that's
where it did break. You really don't understand this stuff very
much, do you? >
You can't see it clearly in this pic, but the valve had been
snapped off half way up it's stem and then hammered back up into
it's port pocket. It was an instant catastrophic failure that was a
result of a component breakage, and it gave zero warning before it
occurred.
Standard behaviour and what one could reasonably expect. Understand
that, once the valve no longer seats properly, head temperature will
rapidly rise until the fillet area becomes plastic. At that point
the head will detach and the whole process to that point is mere
seconds at WOT. Once that head is detached, then you are in the
realm of catastrophic failure and a valve head being wedged into the
port or wedged into a *new slot* in the *piston* is the usual
outcome. If the valve head cant find a space to hide - the port - it
will make a space to hide - in the piston. That's why this type of
failure is commonly known as *penny in the slot*. >
Despite the nonsensical claims of your mental mate, this is *not*
what happens if a valve has been bent slightly from a piston to
valve clearance issue, as any kind of bent valve will cause an
instant compression loss which will be apparent to the driver. And
I can tell you that had such a compression loss occurred Les would
have shut the car down and got it into the pits to investigate :)
It only needs a slight compression loss from a slight bend and, at
high RPM, there will be more than enough compression to create a
very hot burn and, due to the poor valve seating, that burn will be
blasting through the valve seat further exacerbating the valve head
overheat situation.>
and forced the piston to rock in it's bore which immediately
split the bore and filled the cylinder with coolant.
must have been an aluminum block then
Wrong again Felix. Cast iron block, and split bores in cast iron
blocks are not that uncommon. It's very easy to do with you have a
piston and valve remains fighting for an area that is not big
enough to accommodate them.
For once you are correct. I must say, it was patently obvious.>
I used to split bores on Chev V8 engines from running 40lbs of
boost thought a supercharger :)
Photos or it's more bullshit from you. Oh, and not just you as a
*spectator* at the track.>
Not when you take out piston to valve clearance and then create
valve lofting
valve lofting done properly won't cause piston to head contact,
only valve float or bounce does
Refers to the same thing. Valve *lofting* is when the float is
designed in whereas valve float is an undesired effect at high RPM.
yes so not the same thing
Indeed, one is designed, the other unwanted.>
Yes, as a shim head gasket, ie. thinner than standard for performanceThe old grey motor Holdens were well known for it and it got
destructive if allowed to continue. With valve lofting, on the other
hand, the landing zone on the cam lobe is *curated* so there's no
extreme hammering effects.
Correct. This is a perfect example of your clueless mental mate
trying to pass off technical terms he doesn't understand as
explanations for faults he has no idea about.
through over revving because you (a) reduced clearance with a
shim head gasket
has he ever said he used a shim head gasket?
Nope. That's his invention. The engine used a Toyota competition
head gasket which is made specifically for this particular engine.
It's make to raise the compression by around half a point by being
thinner than a regular composite gasket. It is not a "shim", and
I've never used that
Same effect. It is *thinner*. That was my point.
but the gasket was made for that engine?
gains. And it is the *thinner* bit that has the consequences. >>
term. That's something he made up. Either way, it's irrelevant as
the piston to valve clearances were all checked *without* a gasket
in place.
Nope, not something I made up. Making shit up is your bag. Shim head
gaskets have been known in the trade for as long as I can recall.
https://northernautoparts.com/blog/vintage-chevy-shim-head-gaskets/
For the record, shim head gaskets can be used to restore compression
ratios after head and/or deck machining so it's not a new term by
any means and definitely not a new concept. About that
apprenticeship in auto machining that you claim to have done - I
call bullshit - you don't know stuff of which I would reasonably
expect someone in that industry in particular to be 100% cogniscant.
His continual waffling on this subject is nothing other than an
exercise in the ridiculous by a man who is out of his depth in
understanding the subject matter, but here's the *really* stupid part.
Darren, the only one floundering here is you! Here, take this straw!>
In all his ramblings he has been doing nothing other than trying to
find ways to blame me for the failure of this engine, and in doing
so has
Pardon? Weren't you working on the engine? I am only directing blame
where the responsibility lies!
come up with an endless list of comical excuses as for why the
engine failed with each new one being more ridiculous than the
last. His claims
Same concept all the way through, I have made no change.
of "valve lofting" or over revving" are utterly ridiculous, but
even if by some miracle they were accurate I have no idea how he
could connect me with them given that I wasn't driving the car :)
Nope, always I have been on the same path. I said over revving from
the very beginning, I said lofting, float and bounce from the
beginning, might have mentioned overshoot too - same concept.>
Moreover I have mentioned on a number of occasions that anything
related to the cylinder head also had nothing to do with me as the
head was machined and assembled by a third party. My job, such as
it was, was to
You make a mod, you assemble, you *assume responsibility*, that's
how it works. When you are presented with a completely assembled
head, and you want to make mods to the engine on assembly, it
behooves you to check what others have done before you - even if
that means some dismantling - and it definitely means you will check
such things as seat sealing and valve springs and collets. As I
said, you assemble, you assume responsibility. You modify, you 100%
assume responsibility.
make some modifications to the sump and oil puckup for ground
clearance, to assemble the engine using the parts supplied at the
owner's direction, and to set the valve clearances.
You claim motor mechanic qualifications therefore the customer can
assume you have the technical knowhow. Obviouly Les didn't know what
an inveterate liar you are so, in his assumption that you were
honest *AND QUALIFIED*, he made an ASS out of himself.-a >
That was it. Whatever the cause of the fault, be it valve loftingassume responsibility for the entire job.
(lol :), over revving, broken valve spring, dropped collet, overly
lean mixture or improper tune were all at the hands of someone else
and had *nothing_to_do_with_me* :)
Fingers in the ear singing la la la la. Yeah, right. You do the
job, you
Never ASSUME since you will make an ASS out of YOU and ME. Well,
you're not making an ass out of me Darren, your job, your screwup.
The worst part, you can't even backtrack to find the root cause so
you will repeat such mistakes over and over. You don't know how
lucky the world is when you decided to *retire* and do only your own
work. Now you'll be able to easily hide your next cockups. And there
will be cockups, rest assured of that!
On 1/6/2026 3:54 pm, Axel wrote:
Xeno wrote:Why would he do that? There's no point. It's the piston to valve (when
On 1/6/2026 10:51 am, Axel wrote:
Xeno wrote:
On 31/5/2026 3:34 pm, Axel wrote:
Xeno wrote:
On 29/5/2026 9:53 pm, Noddy wrote:
On 29/05/2026 6:01 pm, jonz wrote:
On 29-May-26 3:05 PM, jonz wrote:
-a-aThe 4A-GE(20), having a *5 valve per cylinder head*,
~~~~~~~~~~~~~~~~~would be actually creating valve loft to increase cylinder >>>>>>>>>>>> fill at high RPM.
Nope, because of smaller/lighter valve size, the chances of >>>>>>>>> lofting in a 5 valve are reduced.... one of the reasons for a >>>>>>>>> 5 valve design in the first place!.
This has been done to death, and the more this mental midget
goes on with this nonsense the more clueless he reveals himself >>>>>>>> to be.
The engine failed catastrophically on the turn in to the chase >>>>>>>> on Conrod Straight at Mount Panarama on the 7th lap of a race. >>>>>>>> Prior to that race the car had done various practice sessions, >>>>>>>> a full day of test and tuning at another track (winton) and two >>>>>>>> separate full dyno sessions without any hint of an issue.
Odd, Daryl clearly stated way back that it was running down
conrod straight when it blew. I have been mentioning conrod
straight many times and he has never questioned it. This looks
to me like your standard modus operandi of waiting a year or
three and then, when memories have faded, *alter the data* over >>>>>>> to where you need it to be. If Daryl had not made that point, I >>>>>>> would never have arrived at the valve lofting conclusion.-a >
The engine had *one* valve fail. It was *not* "creating valve >>>>>>>> loft to
It only takes one. The next one might have been seconds away but >>>>>>> once that first one lets go, nothing more matters because the
engine is dead, dead, dead!
Next point, all high performance high revving engines rely on a >>>>>>> degree of lofting to gain those little bits of extra
performance. The benefits of valve lofting were discovered and
utilised first in the motorcycle racing industry when they first >>>>>>> moved to OHV. It is not deliberately used in today's OHC engines >>>>>>> due to the lightweight valve trains. Today's torque curves are
achieved using precise static valve lift profiles and variable
valve timing rather than relying on dynamic lofting. That said, >>>>>>> a very high speed run down conrod straight in a high gear at WOT >>>>>>> is where you are most likely to over rev the engine and see some >>>>>>> unwanted lofting. This is a point I made at the very beginning
when Daryl first mention the point at which the failure occurred. >>>>>>>
increase cylinder fill" which is about as nonsensical a claim >>>>>>>> as one can make. It failed because it stuck a valve in it's
guide at full lift
how does he know? could have been valve float
It failed because the head fell off due to piston contact and
subsequent overheating at the fillet, the hottest point of the
valve. Happens in moments when at WOT.
only if the valve is open during compression
Or if the valve got a light tap from the piston, enough so the
valve would no longer seat and seal during the compression and
power strokes. That would lead to a loss of valve head cooling, an
instant overheat due to burning>
which broke the valve off at the stem, punched it back up into >>>>>>>> the head
Of course it would punch it up there. A loose valve head hasn't >>>>>>> a lot of room in a combustion chamber when the piston is moving >>>>>>> at 15-30 Mps at high RPM and acting like the meanest hammer you >>>>>>> would ever see.
and forced the piston to rock in it's bore which immediately
split the bore and filled the cylinder with coolant.
must have been an aluminum block then
No, all the 4A-GE engines have cast iron blocks. The cylinder head
is alloy however - and it has 5 valves per cylinder.>
Irrelevant, that all happened post the initial cause.>
Daryl may still have the video of the thing when it failed
where the engine changed note and trailed a huge plume of white >>>>>>>> smoke out of it's pipe. It was an instant component breakage
which is not unknown in the world of motorsport :)
Not when you take out piston to valve clearance and then create >>>>>>> valve lofting
valve lofting done properly won't cause piston to head contact,
only valve float or bounce does
Correct. *Done properly* are the operative words. The engine has
to be considered as a system and any single change will affect the
system and its related components. Therefore any change has to be
sympathetic to all aspects of the engine, not just one single
aspect.>
through over revving because you (a) reduced clearance with a
shim head gasket
has he ever said he used a shim head gasket?
Yes, he did.
no, he just said he used the proper gasket
No, he used a thinner gasket than standard.
His words;
Nope. That's his invention. The engine used a Toyota competition
head gasket which is made specifically for this particular engine.
It's make to raise the compression by around half a point by being
thinner than a regular composite gasket. It is not a "shim", and
I've never used that
It is thinner than standard so the general term is a *shim head
gasket*.>
That was my point from the beginning. Engines typically have up to
0.100" piston to valve *static* clearance. Performance engines,
like the $A-GE(20), typically have a bit less but employ much more
rigorous *valve control*. Take some of that clearance, up to
0.020" in the case of a shim head gasket, and the piston can hit
the valve in extreme circumstances - and flat out on conrod
straight is an extreme circumstance. When Daryl indicated the
location of the blowup, the cause became immediately apparent to
me. Affect valve cooling in such a circumstance and the valve head
will overheat and drop off *in seconds*. That, of course, will
trigger a catastrophic failure, as could be seen in the photos.
Darren claims he just fitted the head. I call bullshit on that. If
I were asked to do a job like that I would have pulled all the
valves and checked them out and I would have checked their sealing
and clearances.
unless you had full confidence in whoever did the head and knew
what was done
He didn't even know who that person was.>
He used a thinner head gasket than standard, he even says that inI would have likely fitted lighter and stronger valves that were
much less likely to loft and/or bounce.
What Darren forgot was that removing head gasket thickness
automatically increases the compression ratio. That's done in
order to increase power and that power will come at increased
revs. Therein hangs the tale. >
and (b) didn't take counter measures, ie. lighter valves,
stronger springs, different cam profile. It happens to clowns
like you all the time.
Conrod straight is known for such failures because, quite
simply, it is possible to over rev the engine when running
downhill, WOT, at speed.
anyhow, since he only fitted the head as supplied, and used the
correct gasket, the engine failure is hardly his fault
his recent bullshit.
https://northernautoparts.com/blog/vintage-chevy-shim-head-gaskets/
A thinner head gasket than standard is called a *shim head gasket*.
It's a term I have known and used since my apprenticeship days.
See my recent post on taking responsibility of a job.
but he also said he checked the valve clearances without the gasket
in place
open fully) clearances that are the critical point here. And for that
you would want the head gasket in situ.
Oh BTW, Darren said he checked piston the valve clearances but only
long after I made the point and Darren had stated he couldn't work out
how to do them. Darren lies so lets assume he didn't check, safe
assumption. Also, when you are working on an unknown engine, and
expecting to bump up compressions with a shim head gasket, you might
want to know if the head had been planed. Any amount shaved off the
head *reduces* the piston to valve clearance. Might want to check too
if the block deck had ever been machined as, again, that can
negatively affect the piston to valve clearance.
These are the sort of things you do when you're the dummy who gets to
finish off a job that someone else started. You have no idea what's
*really* been done, if it's even been done properly or done at all.
So, you check, check, check. That's why any mechanic in a workshop
hates taking on a job someone else started. It always takes long than
if you had done the job from start to finish. Remember, you didn't do
the disassembly so have to guess on the reassembly order of operations.
On 1/06/2026 3:51 pm, Axel wrote:
A 4A-GE valve at full lift cannot strike the piston.
I would think so. full lift would be a normal position for it. it
would have to go beyond full lift. ie, bounce
If you think that then you would be wrong, just like your mental mate.
It's all about timing. Under normal operation an exhaust valve is at or
near full lift when a piston is near the bottom of it's bore and on the
way up. As the piston travels towards the top of the bore the valve
begins to close, to the point where by the time the piston gets to top
dead centre the valve is almost shut save for a small amount of opening during the overlap between the inlet and exhaust valves. In some cases
where clearance is needed for this overlap open period pistons have
reliefs cut into their crowns to accommodate this.
That's under normal operation.
Under *abnormal* operation, a valve is open when it *shouldn't* be, and that's a problem. For example, a valve can get stuck in it's guide,
which is invariably caused by insufficient clearance on the stem. This happens quite a bit when people run their clearances a tad on the tight
side, and when it does it usually occurs with the valve at full lift as
while the "grab" of the guide isn't sufficient to stop the valve from
opening when the camshaft is forcing it to, the valve spring pressure
isn't sufficient to pull the valve back if it's jammed open. The net
result is a valve hanging a long way down into the bore with a piston
rapidly heading towards it, and a collision between the two is inevitable.
But that's not the only fault that can cause such a failure. A broken
valve spring will do it, and a dropped valve will also cause such a
problem. However in both of those cases what's more likely is that the
valve will fall into the cylinder completely and then be smacked up by
the piston. In this case the remains of the valve stem were still in the valve guide, suggesting that the valve was jammed open in the guide when
the piston hit it.
Again Darren, you have shown yourself to be truly clueless,
impeccably so! The 4A-GE series are *NOT* interference engines. A
valve at full lift (normal) *cannot* contact the piston. The only
way the piston could ever contact a valve head is if the valve had
*extended travel*, as in when valve float or lofting occurs.>
that's my understanding
And you are both wrong, for all the reasons I mentioned above.
Under normal operation a valve won't hit a piston. But this engine died because of a *malfunction*. This is the point you're not getting Felix.
This was the result of a component failure.
As I said, it's all about timing. The 20 valve 4A-GE is an
"interference" type engine, which means that if a valve is open in the
cycle when it shouldn't be, a piston will very definitely hit it.
On 1/06/2026 1:38 pm, Axel wrote:
Noddy wrote:
This is the moron you're trying to argue sense with.
at least I can have a sensible civil discussion with him, unlike with you
You call this sensible? You're questioning his bullshit and he's just throwing more at you to try to shut you up :)
You can carry on with this as much as you like Felix, but the essential arithmetic here is that *all* of his theories as to how this was my
fault are a complete and utter nonsense.
His claim that the engine was over-revved has nothing to do with me
given that I wasn't driving the car, but he had no idea what rpm it was actually doing and what it was capable of making it difficult to
understand how he could reach that conclusion.
His belief that the "only* way for a valve to hit a piston was by
"lofting" or "bounce" or whatever other fanciful reason is as ridiculous
as his belief that the 20 valve black top was a non interference engine :)
There's been a shitload of other ridiculous claims, but his greatest one being that a lack of piston to valve clearance caused a bent valve which then overheated and caused the valve head to fall off is the most
comical, and I'll tell you why. If the engine *did* suffer from a bent valve, then that would have caused an instant loss of compression
resulting in a dead cylinder. That would have resulted in an immediate
25% loss of power than the driver/owner would have noticed instantly and
got off the throttle and brought the car in to investigate. Moreover,
even if he'd kept driving it a cylinder with no compression is not going
to fire and generate heat meaning that it's ability to heat up the bent valve to the point of melting and having the head fall off is absolutely fucking *nil* :)
It's ludicrous. Burnt valves in car engines is not an uncommon
occurance, and when it does happen this is the usual result:
https://carfromjapan.com/wp-content/uploads/2023/09/burnt-exhaust-
valve-symptoms-1024x683.jpg
See that exhaust valve with the chunk missing out of it Felix? There are
a number of causes for it, but a common one is carbon build up on a seat that prevents the valve from sealing correctly, which in turn prevents
the heat in the valve from being adequately passed into the head to cool
it. The end result is localised overheating which will cause the valve
to fail at that spot as you see in the pic.
What *doesn't happen is the valve get hot enough for the head to fall
off, and the reason for that is because once the engine loses it's
ability to hold compression in a given cylinder, that cylinder no longer generates any heat.
This is basic engines 101. You not being aware of it I can appreciate.
Your mental mate not understanding is inexcusable for someone who claims they were once a "trade teacher" :)
On 1/06/2026 5:44 pm, Keithr0 wrote:
On 1/06/2026 3:12 pm, Xeno wrote:
Again Darren, you have shown yourself to be truly clueless,
impeccably so! The 4A-GE series are *NOT* interference engines. A
valve at full lift (normal) *cannot* contact the piston. The only way
the piston could ever contact a valve head is if the valve had
*extended travel*, as in when valve float or lofting occurs.>
According to your favourite source of information - AI
Whether the Toyota 4AGE 20-valve is an interference engine depends on
which specific version you have:Silvertop (Early 20v): This version is
a non-interference engine. If the timing belt snaps, the valves and
pistons will not collide.Blacktop (Late 20v): This version is an
interference engine. If the timing belt fails, the valves and pistons
will collide, causing significant internal damage.Because 4AGE blocks
and heads are highly interchangeable, many modified engines blur these
lines. For example, putting Blacktop pistons into a Silvertop block
converts it into an interference setup.
It was a blacktop engine. That's all Les used in that car I believe.
On 1/6/2026 5:44 pm, Keithr0 wrote:
On 1/06/2026 3:12 pm, Xeno wrote:The engine concerned was a whitetop and I saw valve cutouts
Again Darren, you have shown yourself to be truly clueless,
impeccably so! The 4A-GE series are *NOT* interference engines. A
valve at full lift (normal) *cannot* contact the piston. The only way
the piston could ever contact a valve head is if the valve had
*extended travel*, as in when valve float or lofting occurs.>
According to your favourite source of information - AI
Whether the Toyota 4AGE 20-valve is an interference engine depends on
which specific version you have:Silvertop (Early 20v): This version is
a non-interference engine. If the timing belt snaps, the valves and
pistons will not collide.Blacktop (Late 20v): This version is an
interference engine. If the timing belt fails, the valves and pistons
will collide, causing significant internal damage.Because 4AGE blocks
and heads are highly interchangeable, many modified engines blur these
lines. For example, putting Blacktop pistons into a Silvertop block
converts it into an interference setup.
Xeno wrote:
On 1/6/2026 3:51 pm, Axel wrote:
Xeno wrote:
On 31/5/2026 7:51 pm, Noddy wrote:
On 31/05/2026 3:34 pm, Axel wrote:
Xeno wrote:
increase cylinder fill" which is about as nonsensical a claim as >>>>>>>> one can make. It failed because it stuck a valve in it's guide >>>>>>>> at full lift
how does he know? could have been valve float
It *wasn't* "valve float" Felix, and to make such a claim shows
that you
You don't have a clue Darren. Your copout was calling it a faulty
valve.
have no understanding of what it is or how it works.
Your conclusion - faulty valve - the standard copout from those
without a clue and one guaranteed to generate an encore!>
A 4A-GE valve at full lift cannot strike the piston.It failed because the head fell off due to piston contact and
subsequent overheating at the fillet, the hottest point of the
valve. Happens in moments when at WOT.
only if the valve is open during compression
Nope. As I said, it was a valve as full lift striking the piston which >>>>
I would think so. full lift would be a normal position for it. it
would have to go beyond full lift. ie, bounce
That's what the piston cutouts are for.
caused the engine failure. That much is obvious to anyone with an
ounce of experience (which would *not* be your mental mate). The
only point of conjecture is why the valve was *at* full lift when
the piston hit it, and there are a few reasons for that. It could
have broken a valve spring, it could have dropped a collet, and it
could have had a tight guide that saw the valve "grab". What it
most definitely was *not* was a result of "loft" or a mechanical
piston to valve clearance issue.
Again Darren, you have shown yourself to be truly clueless,
impeccably so! The 4A-GE series are *NOT* interference engines. A
valve at full lift (normal) *cannot* contact the piston. The only
way the piston could ever contact a valve head is if the valve had
*extended travel*, as in when valve float or lofting occurs.>
that's my understanding
I have shown these pictures before Felix, but as usual you have the >>>>> retention ability of a dead goldfish. This is the type of valve
failure you get from a minor piston to valve clearance issue, and
it's commonly seen whenever an interference type engine breaks a
timing belt:
See above, you can break the belt on a 4A-GE and the valves will not
hit pistons. The only way a 4A-GE valve can hit a piston is if it's
travel gets extended beyond what the cam will lift it. (Read: float,
lofting, overshoot)>
as per my comment above
https://ibb.co/mcKy0q5
As can be seen, the valves in this picture are not bent severely,
but certainly bent enough to cause an instant loss of compression
resulting in a dead cylinder. That's *not* what happened in this case. >>>>>
This is what happened:
https://ibb.co/cwxR1yL
That valve came away at the fillet, the hottest point of the valve
and it can be clearly seen in your pic. That's where I would expect
it to break given the circumstances I outlined and indeed that's
where it did break. You really don't understand this stuff very
much, do you? >
You can't see it clearly in this pic, but the valve had been
snapped off half way up it's stem and then hammered back up into
it's port pocket. It was an instant catastrophic failure that was a >>>>> result of a component breakage, and it gave zero warning before it
occurred.
Standard behaviour and what one could reasonably expect. Understand
that, once the valve no longer seats properly, head temperature will
rapidly rise until the fillet area becomes plastic. At that point
the head will detach and the whole process to that point is mere
seconds at WOT. Once that head is detached, then you are in the
realm of catastrophic failure and a valve head being wedged into the
port or wedged into a *new slot* in the *piston* is the usual
outcome. If the valve head cant find a space to hide - the port - it
will make a space to hide - in the piston. That's why this type of
failure is commonly known as *penny in the slot*. >
Despite the nonsensical claims of your mental mate, this is *not*
what happens if a valve has been bent slightly from a piston to
valve clearance issue, as any kind of bent valve will cause an
instant compression loss which will be apparent to the driver. And
I can tell you that had such a compression loss occurred Les would
have shut the car down and got it into the pits to investigate :)
It only needs a slight compression loss from a slight bend and, at
high RPM, there will be more than enough compression to create a
very hot burn and, due to the poor valve seating, that burn will be
blasting through the valve seat further exacerbating the valve head
overheat situation.>
and forced the piston to rock in it's bore which immediately
split the bore and filled the cylinder with coolant.
must have been an aluminum block then
Wrong again Felix. Cast iron block, and split bores in cast iron
blocks are not that uncommon. It's very easy to do with you have a
piston and valve remains fighting for an area that is not big
enough to accommodate them.
For once you are correct. I must say, it was patently obvious.>
I used to split bores on Chev V8 engines from running 40lbs of
boost thought a supercharger :)
Photos or it's more bullshit from you. Oh, and not just you as a
*spectator* at the track.>
Not when you take out piston to valve clearance and then create >>>>>>> valve lofting
valve lofting done properly won't cause piston to head contact,
only valve float or bounce does
Refers to the same thing. Valve *lofting* is when the float is
designed in whereas valve float is an undesired effect at high RPM.
yes so not the same thing
Indeed, one is designed, the other unwanted.>
Yes, as a shim head gasket, ie. thinner than standard for performanceThe old grey motor Holdens were well known for it and it got
destructive if allowed to continue. With valve lofting, on the other
hand, the landing zone on the cam lobe is *curated* so there's no
extreme hammering effects.
Correct. This is a perfect example of your clueless mental mate
trying to pass off technical terms he doesn't understand as
explanations for faults he has no idea about.
through over revving because you (a) reduced clearance with a
shim head gasket
has he ever said he used a shim head gasket?
Nope. That's his invention. The engine used a Toyota competition
head gasket which is made specifically for this particular engine.
It's make to raise the compression by around half a point by being
thinner than a regular composite gasket. It is not a "shim", and
I've never used that
Same effect. It is *thinner*. That was my point.
but the gasket was made for that engine?
gains. And it is the *thinner* bit that has the consequences. >>
but if it's designed to be used with that engine one would be entitled
to assume it's safe for use on that engine without causing harm. why
else would it be made? to be used with a normal gasket to increase
gasket thickness perhaps??
term. That's something he made up. Either way, it's irrelevant as
the piston to valve clearances were all checked *without* a gasket
in place.
Nope, not something I made up. Making shit up is your bag. Shim head
gaskets have been known in the trade for as long as I can recall.
https://northernautoparts.com/blog/vintage-chevy-shim-head-gaskets/
For the record, shim head gaskets can be used to restore compression
ratios after head and/or deck machining so it's not a new term by
any means and definitely not a new concept. About that
apprenticeship in auto machining that you claim to have done - I
call bullshit - you don't know stuff of which I would reasonably
expect someone in that industry in particular to be 100% cogniscant.
Darren, the only one floundering here is you! Here, take this straw!> >>>>> In all his ramblings he has been doing nothing other than trying to >>>>> find ways to blame me for the failure of this engine, and in doing
His continual waffling on this subject is nothing other than an
exercise in the ridiculous by a man who is out of his depth in
understanding the subject matter, but here's the *really* stupid part. >>>>
so has
Pardon? Weren't you working on the engine? I am only directing blame
where the responsibility lies!
come up with an endless list of comical excuses as for why the
engine failed with each new one being more ridiculous than the
last. His claims
Same concept all the way through, I have made no change.
of "valve lofting" or over revving" are utterly ridiculous, but
even if by some miracle they were accurate I have no idea how he
could connect me with them given that I wasn't driving the car :)
Nope, always I have been on the same path. I said over revving from
the very beginning, I said lofting, float and bounce from the
beginning, might have mentioned overshoot too - same concept.>
Moreover I have mentioned on a number of occasions that anything
related to the cylinder head also had nothing to do with me as the
head was machined and assembled by a third party. My job, such as
it was, was to
You make a mod, you assemble, you *assume responsibility*, that's
how it works. When you are presented with a completely assembled
head, and you want to make mods to the engine on assembly, it
behooves you to check what others have done before you - even if
that means some dismantling - and it definitely means you will check
such things as seat sealing and valve springs and collets. As I
said, you assemble, you assume responsibility. You modify, you 100%
assume responsibility.
make some modifications to the sump and oil puckup for ground
clearance, to assemble the engine using the parts supplied at the
owner's direction, and to set the valve clearances.
You claim motor mechanic qualifications therefore the customer can
assume you have the technical knowhow. Obviouly Les didn't know what
an inveterate liar you are so, in his assumption that you were
honest *AND QUALIFIED*, he made an ASS out of himself.-a >
That was it. Whatever the cause of the fault, be it valve loftingassume responsibility for the entire job.
(lol :), over revving, broken valve spring, dropped collet, overly
lean mixture or improper tune were all at the hands of someone else >>>>> and had *nothing_to_do_with_me* :)
Fingers in the ear singing la la la la. Yeah, right. You do the
job, you
Never ASSUME since you will make an ASS out of YOU and ME. Well,
you're not making an ass out of me Darren, your job, your screwup.
The worst part, you can't even backtrack to find the root cause so
you will repeat such mistakes over and over. You don't know how
lucky the world is when you decided to *retire* and do only your own
work. Now you'll be able to easily hide your next cockups. And there
will be cockups, rest assured of that!
Xeno wrote:
Yes, as a shim head gasket, ie. thinner than standard for performance
gains. And it is the *thinner* bit that has the consequences. >>
but if it's designed to be used with that engine one would be entitled
to assume it's safe for use on that engine without causing harm. why
else would it be made? to be used with a normal gasket to increase
gasket thickness perhaps??
Xeno wrote:
On 1/6/2026 3:54 pm, Axel wrote:
Xeno wrote:Why would he do that? There's no point. It's the piston to valve (when
On 1/6/2026 10:51 am, Axel wrote:
Xeno wrote:
On 31/5/2026 3:34 pm, Axel wrote:
Xeno wrote:
On 29/5/2026 9:53 pm, Noddy wrote:
On 29/05/2026 6:01 pm, jonz wrote:
On 29-May-26 3:05 PM, jonz wrote:
-a-aThe 4A-GE(20), having a *5 valve per cylinder head*, >>>>>>>>>>>>> would be actually creating valve loft to increase cylinder >>>>>>>>>>>>> fill at high RPM.
~~~~~~~~~~~~~~~~~
Nope, because of smaller/lighter valve size, the chances of >>>>>>>>>> lofting in a 5 valve are reduced.... one of the reasons for a >>>>>>>>>> 5 valve design in the first place!.
This has been done to death, and the more this mental midget >>>>>>>>> goes on with this nonsense the more clueless he reveals himself >>>>>>>>> to be.
The engine failed catastrophically on the turn in to the chase >>>>>>>>> on Conrod Straight at Mount Panarama on the 7th lap of a race. >>>>>>>>> Prior to that race the car had done various practice sessions, >>>>>>>>> a full day of test and tuning at another track (winton) and two >>>>>>>>> separate full dyno sessions without any hint of an issue.
Odd, Daryl clearly stated way back that it was running down
conrod straight when it blew. I have been mentioning conrod
straight many times and he has never questioned it. This looks >>>>>>>> to me like your standard modus operandi of waiting a year or
three and then, when memories have faded, *alter the data* over >>>>>>>> to where you need it to be. If Daryl had not made that point, I >>>>>>>> would never have arrived at the valve lofting conclusion.-a > >>>>>>>>> The engine had *one* valve fail. It was *not* "creating valve >>>>>>>>> loft to
It only takes one. The next one might have been seconds away but >>>>>>>> once that first one lets go, nothing more matters because the >>>>>>>> engine is dead, dead, dead!
Next point, all high performance high revving engines rely on a >>>>>>>> degree of lofting to gain those little bits of extra
performance. The benefits of valve lofting were discovered and >>>>>>>> utilised first in the motorcycle racing industry when they first >>>>>>>> moved to OHV. It is not deliberately used in today's OHC engines >>>>>>>> due to the lightweight valve trains. Today's torque curves are >>>>>>>> achieved using precise static valve lift profiles and variable >>>>>>>> valve timing rather than relying on dynamic lofting. That said, >>>>>>>> a very high speed run down conrod straight in a high gear at WOT >>>>>>>> is where you are most likely to over rev the engine and see some >>>>>>>> unwanted lofting. This is a point I made at the very beginning >>>>>>>> when Daryl first mention the point at which the failure occurred. >>>>>>>>
increase cylinder fill" which is about as nonsensical a claim >>>>>>>>> as one can make. It failed because it stuck a valve in it's >>>>>>>>> guide at full lift
how does he know? could have been valve float
It failed because the head fell off due to piston contact and >>>>>>>> subsequent overheating at the fillet, the hottest point of the >>>>>>>> valve. Happens in moments when at WOT.
only if the valve is open during compression
Or if the valve got a light tap from the piston, enough so the
valve would no longer seat and seal during the compression and
power strokes. That would lead to a loss of valve head cooling, an >>>>>> instant overheat due to burning>
which broke the valve off at the stem, punched it back up into >>>>>>>>> the head
Of course it would punch it up there. A loose valve head hasn't >>>>>>>> a lot of room in a combustion chamber when the piston is moving >>>>>>>> at 15-30 Mps at high RPM and acting like the meanest hammer you >>>>>>>> would ever see.
and forced the piston to rock in it's bore which immediately >>>>>>>>> split the bore and filled the cylinder with coolant.
must have been an aluminum block then
No, all the 4A-GE engines have cast iron blocks. The cylinder head >>>>>> is alloy however - and it has 5 valves per cylinder.>
Irrelevant, that all happened post the initial cause.>
Daryl may still have the video of the thing when it failed
where the engine changed note and trailed a huge plume of white >>>>>>>>> smoke out of it's pipe. It was an instant component breakage >>>>>>>>> which is not unknown in the world of motorsport :)
Not when you take out piston to valve clearance and then create >>>>>>>> valve lofting
valve lofting done properly won't cause piston to head contact, >>>>>>> only valve float or bounce does
Correct. *Done properly* are the operative words. The engine has
to be considered as a system and any single change will affect the >>>>>> system and its related components. Therefore any change has to be >>>>>> sympathetic to all aspects of the engine, not just one single
aspect.>
through over revving because you (a) reduced clearance with a >>>>>>>> shim head gasket
has he ever said he used a shim head gasket?
Yes, he did.
no, he just said he used the proper gasket
No, he used a thinner gasket than standard.
His words;
Nope. That's his invention. The engine used a Toyota competition
head gasket which is made specifically for this particular engine. >>>> >>> It's make to raise the compression by around half a point by being >>>> >>> thinner than a regular composite gasket. It is not a "shim", and
I've never used that
It is thinner than standard so the general term is a *shim head
gasket*.>
That was my point from the beginning. Engines typically have up to >>>>>> 0.100" piston to valve *static* clearance. Performance engines,
like the $A-GE(20), typically have a bit less but employ much more >>>>>> rigorous *valve control*. Take some of that clearance, up to
0.020" in the case of a shim head gasket, and the piston can hit
the valve in extreme circumstances - and flat out on conrod
straight is an extreme circumstance. When Daryl indicated the
location of the blowup, the cause became immediately apparent to
me. Affect valve cooling in such a circumstance and the valve head >>>>>> will overheat and drop off *in seconds*. That, of course, will
trigger a catastrophic failure, as could be seen in the photos.
Darren claims he just fitted the head. I call bullshit on that. If >>>>>> I were asked to do a job like that I would have pulled all the
valves and checked them out and I would have checked their sealing >>>>>> and clearances.
unless you had full confidence in whoever did the head and knew
what was done
He didn't even know who that person was.>
He used a thinner head gasket than standard, he even says that inI would have likely fitted lighter and stronger valves that were
much less likely to loft and/or bounce.
What Darren forgot was that removing head gasket thickness
automatically increases the compression ratio. That's done in
order to increase power and that power will come at increased
revs. Therein hangs the tale. >
and (b) didn't take counter measures, ie. lighter valves,
stronger springs, different cam profile. It happens to clowns >>>>>>>> like you all the time.
Conrod straight is known for such failures because, quite
simply, it is possible to over rev the engine when running
downhill, WOT, at speed.
anyhow, since he only fitted the head as supplied, and used the
correct gasket, the engine failure is hardly his fault
his recent bullshit.
https://northernautoparts.com/blog/vintage-chevy-shim-head-gaskets/
A thinner head gasket than standard is called a *shim head gasket*.
It's a term I have known and used since my apprenticeship days.
See my recent post on taking responsibility of a job.
but he also said he checked the valve clearances without the gasket
in place
open fully) clearances that are the critical point here. And for that
you would want the head gasket in situ.
well if there's no issue without a gasket, there's not going to be one
with a gasket fitted, as the gasket only increases the size of the combustion chamber
Oh BTW, Darren said he checked piston the valve clearances but only
long after I made the point and Darren had stated he couldn't work out
how to do them. Darren lies so lets assume he didn't check, safe
assumption. Also, when you are working on an unknown engine, and
expecting to bump up compressions with a shim head gasket, you might
want to know if the head had been planed. Any amount shaved off the
head *reduces* the piston to valve clearance. Might want to check too
if the block deck had ever been machined as, again, that can
negatively affect the piston to valve clearance.
yep
These are the sort of things you do when you're the dummy who gets to
finish off a job that someone else started. You have no idea what's
*really* been done, if it's even been done properly or done at all.
So, you check, check, check. That's why any mechanic in a workshop
hates taking on a job someone else started. It always takes long than
if you had done the job from start to finish. Remember, you didn't do
the disassembly so have to guess on the reassembly order of operations.
did he say why he had been given the job?
Xeno wrote:
Why would he do that? There's no point. It's the piston to valve (when
open fully) clearances that are the critical point here. And for that
you would want the head gasket in situ.
well if there's no issue without a gasket, there's not going to be one
with a gasket fitted, as the gasket only increases the size of the combustion chamber
Oh BTW, Darren said he checked piston the valve clearances but only
long after I made the point and Darren had stated he couldn't work out
how to do them. Darren lies so lets assume he didn't check, safe
assumption. Also, when you are working on an unknown engine, and
expecting to bump up compressions with a shim head gasket, you might
want to know if the head had been planed. Any amount shaved off the
head *reduces* the piston to valve clearance. Might want to check too
if the block deck had ever been machined as, again, that can
negatively affect the piston to valve clearance.
yep
These are the sort of things you do when you're the dummy who gets to
finish off a job that someone else started. You have no idea what's
*really* been done, if it's even been done properly or done at all.
So, you check, check, check. That's why any mechanic in a workshop
hates taking on a job someone else started. It always takes long than
if you had done the job from start to finish. Remember, you didn't do
the disassembly so have to guess on the reassembly order of operations.
did he say why he had been given the job?
On 1/06/2026 5:53 pm, Xeno wrote:
A whitetop?Whether the Toyota 4AGE 20-valve is an interference engine depends onThe engine concerned was a whitetop and I saw valve cutouts
which specific version you have:Silvertop (Early 20v): This version
is a non-interference engine. If the timing belt snaps, the valves
and pistons will not collide.Blacktop (Late 20v): This version is an
interference engine. If the timing belt fails, the valves and pistons
will collide, causing significant internal damage.Because 4AGE blocks
and heads are highly interchangeable, many modified engines blur
these lines. For example, putting Blacktop pistons into a Silvertop
block converts it into an interference setup.
On 1/06/2026 5:53 pm, Xeno wrote:
On 1/6/2026 5:44 pm, Keithr0 wrote:A whitetop?
On 1/06/2026 3:12 pm, Xeno wrote:The engine concerned was a whitetop and I saw valve cutouts
Again Darren, you have shown yourself to be truly clueless,
impeccably so! The 4A-GE series are *NOT* interference engines. A
valve at full lift (normal) *cannot* contact the piston. The only
way the piston could ever contact a valve head is if the valve had
*extended travel*, as in when valve float or lofting occurs.>
According to your favourite source of information - AI
Whether the Toyota 4AGE 20-valve is an interference engine depends on
which specific version you have:Silvertop (Early 20v): This version
is a non-interference engine. If the timing belt snaps, the valves
and pistons will not collide.Blacktop (Late 20v): This version is an
interference engine. If the timing belt fails, the valves and pistons
will collide, causing significant internal damage.Because 4AGE blocks
and heads are highly interchangeable, many modified engines blur
these lines. For example, putting Blacktop pistons into a Silvertop
block converts it into an interference setup.
On 1/06/2026 3:12 pm, Xeno wrote:
Again Darren, you have shown yourself to be truly clueless, impeccably
so! The 4A-GE series are *NOT* interference engines. A valve at full
lift (normal) *cannot* contact the piston. The only way the piston
could ever contact a valve head is if the valve had *extended travel*,
as in when valve float or lofting occurs.>
According to your favourite source of information - AI
Whether the Toyota 4AGE 20-valve is an interference engine depends on
which specific version you have:Silvertop (Early 20v): This version is a non-interference engine. If the timing belt snaps, the valves and
pistons will not collide.Blacktop (Late 20v): This version is an interference engine. If the timing belt fails, the valves and pistons
will collide, causing significant internal damage.Because 4AGE blocks
and heads are highly interchangeable, many modified engines blur these lines. For example, putting Blacktop pistons into a Silvertop block
converts it into an interference setup.
On 1/06/2026 5:53 pm, Xeno wrote:
On 1/6/2026 5:44 pm, Keithr0 wrote:A whitetop?
On 1/06/2026 3:12 pm, Xeno wrote:The engine concerned was a whitetop and I saw valve cutouts
Again Darren, you have shown yourself to be truly clueless,
impeccably so! The 4A-GE series are *NOT* interference engines. A
valve at full lift (normal) *cannot* contact the piston. The only
way the piston could ever contact a valve head is if the valve had
*extended travel*, as in when valve float or lofting occurs.>
According to your favourite source of information - AI
Whether the Toyota 4AGE 20-valve is an interference engine depends on
which specific version you have:Silvertop (Early 20v): This version
is a non-interference engine. If the timing belt snaps, the valves
and pistons will not collide.Blacktop (Late 20v): This version is an
interference engine. If the timing belt fails, the valves and pistons
will collide, causing significant internal damage.Because 4AGE blocks
and heads are highly interchangeable, many modified engines blur
these lines. For example, putting Blacktop pistons into a Silvertop
block converts it into an interference setup.
On 1/6/2026 5:44 pm, Keithr0 wrote:
On 1/06/2026 3:12 pm, Xeno wrote:All very true, you can even fit various 4AGE heads onto a 7AFE block to increase capacity to 1.8lts.
Again Darren, you have shown yourself to be truly clueless,
impeccably so! The 4A-GE series are *NOT* interference engines. A
valve at full lift (normal) *cannot* contact the piston. The only way
the piston could ever contact a valve head is if the valve had
*extended travel*, as in when valve float or lofting occurs.>
According to your favourite source of information - AI
Whether the Toyota 4AGE 20-valve is an interference engine depends on
which specific version you have:Silvertop (Early 20v): This version is
a non-interference engine. If the timing belt snaps, the valves and
pistons will not collide.Blacktop (Late 20v): This version is an
interference engine. If the timing belt fails, the valves and pistons
will collide, causing significant internal damage.Because 4AGE blocks
and heads are highly interchangeable, many modified engines blur these
lines. For example, putting Blacktop pistons into a Silvertop block
converts it into an interference setup.
LOL, I wonder how many 4AGE's he has worked on?
I haven't worked on one this week but did last week, it was a silver top
20V in a Westfield.
-a-a AI OverviewSo the shim is used, presumably with a normal gasket to INCREASE the the
-a-a Head gasket shim plates (also called spacer shims or head
-a-a savers) are rigid metal plates placed between the engine
-a-a block and cylinder head. They are primarily used to correct
-a-a excessive piston protrusion in diesel engines, decrease
-a-a compression ratios for high-boost turbo setups, or salvage
-a-a cylinder heads that have been excessively machined.
On 1/06/2026 5:41 pm, Xeno wrote:
-a-a-a AI OverviewSo the shim is used, presumably with a normal gasket to INCREASE the the valve clearance, not one it's own to DECREASE the clearance.
-a-a-a Head gasket shim plates (also called spacer shims or head
-a-a-a savers) are rigid metal plates placed between the engine
-a-a-a block and cylinder head. They are primarily used to correct
-a-a-a excessive piston protrusion in diesel engines, decrease
-a-a-a compression ratios for high-boost turbo setups, or salvage
-a-a-a cylinder heads that have been excessively machined.
With petrol engines, the spark will always fire the mixture and the
valve will always burn even with much reduced compressions.
VWs wereCompletely irrelevant.
noted for burning valves, then dropping the heads off whilst running. In fact, if you over revved a VW engine on a long downhill run at WOT, you
were quite likely to drop the valve head off on #3 cylinder. That
cylinder always ran hot you see, airflow to it was restricted by the oil cooler.
On 1/06/2026 5:41 pm, Xeno wrote:
-a-a-a AI Overview
-a-a-a Head gasket shim plates (also called spacer shims or head
-a-a-a savers) are rigid metal plates placed between the engine
-a-a-a block and cylinder head. They are primarily used to correct
-a-a-a excessive piston protrusion in diesel engines, decrease
-a-a-a compression ratios for high-boost turbo setups, or salvage
-a-a-a cylinder heads that have been excessively machined.
So the shim is used, presumably with a normal gasket to INCREASE the the valve clearance, not one it's own to DECREASE the clearance.
On 2/06/2026 11:39 am, Keithr0 wrote:
On 1/06/2026 5:41 pm, Xeno wrote:
-a-a-a AI Overview
-a-a-a Head gasket shim plates (also called spacer shims or head
-a-a-a savers) are rigid metal plates placed between the engine
-a-a-a block and cylinder head. They are primarily used to correct
-a-a-a excessive piston protrusion in diesel engines, decrease
-a-a-a compression ratios for high-boost turbo setups, or salvage
-a-a-a cylinder heads that have been excessively machined.
So the shim is used, presumably with a normal gasket to INCREASE the
the valve clearance, not one it's own to DECREASE the clearance.
Yep. In Petrol applications head gasket shims are most commonly used in forced induction applications where one is looking to reduce the static compression ratio to allow for boost. It's a quick and dirty way of achieving the goal without having to pull the engine down and replace pistons.
On 1/06/2026 7:32 pm, Xeno wrote:
With petrol engines, the spark will always fire the mixture and the
valve will always burn even with much reduced compressions.
But there would still be a significant drop in power prior to the
eventual disaster. The driver would certainly notice that particularly
when pushing hard in a race.
VWs were noted for burning valves, then dropping the heads off whilst
running. In fact, if you over revved a VW engine on a long downhill
run at WOT, you were quite likely to drop the valve head off on #3
cylinder. That cylinder always ran hot you see, airflow to it was
restricted by the oil cooler.
Completely irrelevant.
On 2/06/2026 11:55 am, Noddy wrote:
On 2/06/2026 11:39 am, Keithr0 wrote:I was reading the other day that tuners in the US are taking old Prius engines, fitting them with a reground cam shaft converting the donk to a high compression Otto cycle motor.
On 1/06/2026 5:41 pm, Xeno wrote:
-a-a-a AI Overview
-a-a-a Head gasket shim plates (also called spacer shims or head
-a-a-a savers) are rigid metal plates placed between the engine
-a-a-a block and cylinder head. They are primarily used to correct
-a-a-a excessive piston protrusion in diesel engines, decrease
-a-a-a compression ratios for high-boost turbo setups, or salvage
-a-a-a cylinder heads that have been excessively machined.
So the shim is used, presumably with a normal gasket to INCREASE the
the valve clearance, not one it's own to DECREASE the clearance.
Yep. In Petrol applications head gasket shims are most commonly used
in forced induction applications where one is looking to reduce the
static compression ratio to allow for boost. It's a quick and dirty
way of achieving the goal without having to pull the engine down and
replace pistons.
On 1/06/2026 5:41 pm, Xeno wrote:
-a-a-a AI OverviewSo the shim is used, presumably with a normal gasket to INCREASE the the valve clearance, not one it's own to DECREASE the clearance.
-a-a-a Head gasket shim plates (also called spacer shims or head
-a-a-a savers) are rigid metal plates placed between the engine
-a-a-a block and cylinder head. They are primarily used to correct
-a-a-a excessive piston protrusion in diesel engines, decrease
-a-a-a compression ratios for high-boost turbo setups, or salvage
-a-a-a cylinder heads that have been excessively machined.
On 2/6/2026 11:39 am, Keithr0 wrote:
On 1/06/2026 5:41 pm, Xeno wrote:
-a-a-a AI OverviewSo the shim is used, presumably with a normal gasket to INCREASE the
-a-a-a Head gasket shim plates (also called spacer shims or head
-a-a-a savers) are rigid metal plates placed between the engine
-a-a-a block and cylinder head. They are primarily used to correct
-a-a-a excessive piston protrusion in diesel engines, decrease
-a-a-a compression ratios for high-boost turbo setups, or salvage
-a-a-a cylinder heads that have been excessively machined.
the valve clearance, not one it's own to DECREASE the clearance.
LOL.
On 1/06/2026 7:32 pm, Xeno wrote:
With petrol engines, the spark will always fire the mixture and the
valve will always burn even with much reduced compressions.
But there would still be a significant drop in power prior to the
eventual disaster. The driver would certainly notice that particularly
when pushing hard in a race.
VWs were noted for burning valves, then dropping the heads off whilstCompletely irrelevant.
running. In fact, if you over revved a VW engine on a long downhill
run at WOT, you were quite likely to drop the valve head off on #3
cylinder. That cylinder always ran hot you see, airflow to it was
restricted by the oil cooler.
On 2/06/2026 11:39 am, Keithr0 wrote:
On 1/06/2026 5:41 pm, Xeno wrote:
-a-a-a AI Overview
-a-a-a Head gasket shim plates (also called spacer shims or head
-a-a-a savers) are rigid metal plates placed between the engine
-a-a-a block and cylinder head. They are primarily used to correct
-a-a-a excessive piston protrusion in diesel engines, decrease
-a-a-a compression ratios for high-boost turbo setups, or salvage
-a-a-a cylinder heads that have been excessively machined.
So the shim is used, presumably with a normal gasket to INCREASE the
the valve clearance, not one it's own to DECREASE the clearance.
Yep. In Petrol applications head gasket shims are most commonly used in forced induction applications where one is looking to reduce the static compression ratio to allow for boost. It's a quick and dirty way of achieving the goal without having to pull the engine down and replace pistons.
On 2/06/2026 11:55 am, Noddy wrote:
On 2/06/2026 11:39 am, Keithr0 wrote:I was reading the other day that tuners in the US are taking old Prius engines, fitting them with a reground cam shaft converting the donk to a high compression Otto cycle motor.
On 1/06/2026 5:41 pm, Xeno wrote:
-a-a-a AI Overview
-a-a-a Head gasket shim plates (also called spacer shims or head
-a-a-a savers) are rigid metal plates placed between the engine
-a-a-a block and cylinder head. They are primarily used to correct
-a-a-a excessive piston protrusion in diesel engines, decrease
-a-a-a compression ratios for high-boost turbo setups, or salvage
-a-a-a cylinder heads that have been excessively machined.
So the shim is used, presumably with a normal gasket to INCREASE the
the valve clearance, not one it's own to DECREASE the clearance.
Yep. In Petrol applications head gasket shims are most commonly used
in forced induction applications where one is looking to reduce the
static compression ratio to allow for boost. It's a quick and dirty
way of achieving the goal without having to pull the engine down and
replace pistons.
On 2/06/2026 12:08 pm, Keithr0 wrote:
On 2/06/2026 11:55 am, Noddy wrote:
On 2/06/2026 11:39 am, Keithr0 wrote:I was reading the other day that tuners in the US are taking old Prius
On 1/06/2026 5:41 pm, Xeno wrote:
-a-a-a AI Overview
-a-a-a Head gasket shim plates (also called spacer shims or head
-a-a-a savers) are rigid metal plates placed between the engine
-a-a-a block and cylinder head. They are primarily used to correct
-a-a-a excessive piston protrusion in diesel engines, decrease
-a-a-a compression ratios for high-boost turbo setups, or salvage
-a-a-a cylinder heads that have been excessively machined.
So the shim is used, presumably with a normal gasket to INCREASE the
the valve clearance, not one it's own to DECREASE the clearance.
Yep. In Petrol applications head gasket shims are most commonly used
in forced induction applications where one is looking to reduce the
static compression ratio to allow for boost. It's a quick and dirty
way of achieving the goal without having to pull the engine down and
replace pistons.
engines, fitting them with a reground cam shaft converting the donk to
a high compression Otto cycle motor.
It takes all kinds :)
On 2/06/2026 11:43 am, Keithr0 wrote:
On 1/06/2026 7:32 pm, Xeno wrote:
With petrol engines, the spark will always fire the mixture and the
valve will always burn even with much reduced compressions.
But there would still be a significant drop in power prior to the
eventual disaster. The driver would certainly notice that particularly
when pushing hard in a race.
Of course they would. As soon as you bend a valve there is an instant
loss of compression creating a dead cylinder. On something like a 1600cc
4 cylinder engine the loss in power would be as significant as suddenly lifting your foot when at full throttle in top gear. Anyone who's ever driven a car who's been fanging along and had a plug lead fall off will
tell you how noticeable the effect of a dead cylinder can be :)
Moreover, the heat generated inside a cylinder with zero compression is virtually nil, as fuel and air is blown straight out of the cylinder
past the bent valve before the plug fires. At worst you might shoot a
flame out of a header pipe, but you most definitely won't build up
enough heat in the cylinder to melt the head off a valve.
The idea is an utter nonsense, and in fact on some competition engines
with individual exhaust pyrometers
a lack of heat is how they tell the engine has an issue :)
VWs were noted for burning valves, then dropping the heads off whilst
running. In fact, if you over revved a VW engine on a long downhill
run at WOT, you were quite likely to drop the valve head off on #3
cylinder. That cylinder always ran hot you see, airflow to it was
restricted by the oil cooler.
Completely irrelevant.
Indeed it is, but as we all know he usually tries to pad out his
nonsensical bullshit with irrelevant anecdotal rubbish.
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