From Newsgroup: rec.crafts.metalworking

I am working on my Briggs and Stratton Flyer project - now at the
"motorwheel" stage. 5HP flathead 6:1 "winch engine" driving 20 inch
wheel direct drive - engine lacks bottom end torque.
I plan on advancing ONLY the intake valve closing event 14 crankshaft
degrees and getting rid of the EZ Spin decompressor bump. (the bump is
already gone - tried advancing the whole cam 14 degrees(one tooth on
52 tooth cam gear) and it ran well but loses 14 degrees of the power
stroke,( blowing it all out the exhaust) Inreased cyl filling from
advanced IVC was more than cancelled out by the short power stroke.
I plan on setting up the fremmel on the milling attachment of the
Myford super 7, chucking the cam in the lathe chuck, with back gear
locked, and manipulating the dremel with x,y, and z axis handwheels to
rough it out then finish it with a diamond hone. I expect to lose
about .015 to .020 lift from the original .233 and virtually double my
600-1000 rpm torque. It should pretty much self limit at just under
2500.
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From Newsgroup: rec.crafts.metalworking

On 7/27/2026 11:19 AM, Clare Snyder wrote:

I am working on my Briggs and Stratton Flyer project - now at the "motorwheel" stage. 5HP flathead 6:1 "winch engine" driving 20 inch
wheel direct drive - engine lacks bottom end torque.
I plan on advancing ONLY the intake valve closing event 14 crankshaft
degrees and getting rid of the EZ Spin decompressor bump. (the bump is already gone - tried advancing the whole cam 14 degrees(one tooth on
52 tooth cam gear) and it ran well but loses 14 degrees of the power
stroke,( blowing it all out the exhaust) Inreased cyl filling from
advanced IVC was more than cancelled out by the short power stroke.
I plan on setting up the fremmel on the milling attachment of the
Myford super 7, chucking the cam in the lathe chuck, with back gear
locked, and manipulating the dremel with x,y, and z axis handwheels to
rough it out then finish it with a diamond hone. I expect to lose
about .015 to .020 lift from the original .233 and virtually double my 600-1000 rpm torque. It should pretty much self limit at just under
2500.

Did you ever do a cranking compression test on the engine before and
after cam phase changes?

Stan
--
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From Newsgroup: rec.crafts.metalworking

On 7/27/2026 8:19 AM, Clare Snyder wrote:

I am working on my Briggs and Stratton Flyer project

Something like that thing on Winky's Workshop?

- now at the

"motorwheel" stage. 5HP flathead 6:1 "winch engine" driving 20 inch
wheel direct drive - engine lacks bottom end torque.

CVT to an intermediate jack shaft really helps with that.

I plan on advancing ONLY the intake valve closing event 14 crankshaft
degrees and getting rid of the EZ Spin decompressor bump. (the bump is already gone - tried advancing the whole cam 14 degrees(one tooth on
52 tooth cam gear) and it ran well but loses 14 degrees of the power
stroke,( blowing it all out the exhaust) Inreased cyl filling from
advanced IVC was more than cancelled out by the short power stroke.

Generally you advance timing with an offset key (if it has a keyed
balancer) giving you a degree or two. Much better than a sudden shift
of 14.

I plan on setting up the fremmel on the milling attachment of the
Myford super 7, chucking the cam in the lathe chuck, with back gear
locked, and manipulating the dremel with x,y, and z axis handwheels to
rough it out then finish it with a diamond hone. I expect to lose
about .015 to .020 lift from the original .233 and virtually double my 600-1000 rpm torque. It should pretty much self limit at just under
2500.

Generally they go the other way with those engines at the cost of engine
life. MORE rpm, with more gas, more air, and a more open exhaust,
elimination of the governor, and stronger valve springs. That is
basically stage 1. Sometimes before upgrading engine internals they
will mill the head for more compression. I've seen YouTube hotrodders
do it on a sanding belt.

Generally, instead of trying to build low end torque with a tiny engine
they built horsepower, and increased the gear ratio and they launched at higher RPM.

Some of the older early videos from guys like Red Beard's Garage and
Cars and Cameras from when they were still doing it mostly for fun
really do some interesting cheap mods on those small engines. Sure a
top fuel mini dragster built around an alcohol fuel turbo charged
predator 670 is entertaining, but I more enjoyed their older shorter
videos where they took an EX21 with basic mods and stretched another 5-7
mph out of it. If you must play with the 670 dropping one bonestock on
an old Paughco Springer frame was more approachable and made it more interesting.

For reference I've got a couple Manco Intruder II carts I bought for the
kids years ago. Even with the Subaru Robin EX21 (6.5hp) they run a CVT
to an intermediate jack shaft and then a tiny gear on the jack shaft to
a giant gear on the drive axle and run only 16 inch tires. They do run turf/sand knobbies, so take off torque is important, but I think they
are locking up at a much higher rpm than you are thinking.

When I was a kid those who were lucky enough to have an old classic 5HP
cart with a simple belt/lever friction clutch were running tiny tires.

I'm not sure an RV cam (long dureation) translates significantly to a
5HP engine, but I am more than happy to learn something. If you are
thinking high lift CAM then that is more geared towards higher RPM power.

I'm just talking. I didn't really analyze your post thoroughly.
--
Bob La Londe
CNC Molds N Stuff
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From Newsgroup: rec.crafts.metalworking

On 7/27/26 11:19 AM, Clare Snyder wrote:

I am working on my Briggs and Stratton Flyer project - now at the "motorwheel" stage. 5HP flathead 6:1 "winch engine" driving 20 inch
wheel direct drive - engine lacks bottom end torque.
I plan on advancing ONLY the intake valve closing event 14 crankshaft
degrees and getting rid of the EZ Spin decompressor bump. (the bump is already gone - tried advancing the whole cam 14 degrees(one tooth on
52 tooth cam gear) and it ran well but loses 14 degrees of the power
stroke,( blowing it all out the exhaust) Inreased cyl filling from
advanced IVC was more than cancelled out by the short power stroke.
I plan on setting up the fremmel on the milling attachment of the
Myford super 7, chucking the cam in the lathe chuck, with back gear
locked, and manipulating the dremel with x,y, and z axis handwheels to
rough it out then finish it with a diamond hone. I expect to lose
about .015 to .020 lift from the original .233 and virtually double my 600-1000 rpm torque. It should pretty much self limit at just under
2500.

Can you grind some off the base circle and get the lost lift (and more)
back? You will have to add length to the follower region (pushrod,
bucket follower, whatever you have) to keep the geometry correct at the
valve tip, I don't know that valve train so can't help there.

There's a engine good discussion website called speedtalk.com
(unfortunately it's been fighting off bots for a week so response time
is very slow at the moment). One of the long time posters goes by SchmidtMotorWorks, he has developed a browser-based set of software for
cam design you might take a look at if you want to evaluate your
proposed shapes. See his announcement at https://www.speed-talk.com/forum/viewtopic.php?t=71686&view=unread#unread
--
Regards,
Carl
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From Newsgroup: rec.crafts.metalworking

On Mon, 27 Jul 2026 14:00:52 -0400, StanWeiss <srweiss1@comcast.net>
wrote:

On 7/27/2026 11:19 AM, Clare Snyder wrote:

I am working on my Briggs and Stratton Flyer project - now at the
"motorwheel" stage. 5HP flathead 6:1 "winch engine" driving 20 inch
wheel direct drive - engine lacks bottom end torque.
I plan on advancing ONLY the intake valve closing event 14 crankshaft
degrees and getting rid of the EZ Spin decompressor bump. (the bump is
already gone - tried advancing the whole cam 14 degrees(one tooth on
52 tooth cam gear) and it ran well but loses 14 degrees of the power
stroke,( blowing it all out the exhaust) Inreased cyl filling from
advanced IVC was more than cancelled out by the short power stroke.
I plan on setting up the fremmel on the milling attachment of the
Myford super 7, chucking the cam in the lathe chuck, with back gear
locked, and manipulating the dremel with x,y, and z axis handwheels to
rough it out then finish it with a diamond hone. I expect to lose
about .015 to .020 lift from the original .233 and virtually double my
600-1000 rpm torque. It should pretty much self limit at just under
2500.

Did you ever do a cranking compression test on the engine before and
after cam phase changes?

Stan

with cam advanced it was OBVIOSLY lower cranking compression. My50
year old screw in tester does not work too well right now.
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From Newsgroup: rec.crafts.metalworking

On Mon, 27 Jul 2026 12:52:43 -0700, Bob La Londe <none@none.com99>
wrote:

On 7/27/2026 8:19 AM, Clare Snyder wrote:

I am working on my Briggs and Stratton Flyer project

Something like that thing on Winky's Workshop?

- now at the

"motorwheel" stage. 5HP flathead 6:1 "winch engine" driving 20 inch
wheel direct drive - engine lacks bottom end torque.

CVT to an intermediate jack shaft really helps with that.

Looks like hell though

I plan on advancing ONLY the intake valve closing event 14 crankshaft
degrees and getting rid of the EZ Spin decompressor bump. (the bump is
already gone - tried advancing the whole cam 14 degrees(one tooth on
52 tooth cam gear) and it ran well but loses 14 degrees of the power
stroke,( blowing it all out the exhaust) Inreased cyl filling from
advanced IVC was more than cancelled out by the short power stroke.

Generally you advance timing with an offset key (if it has a keyed
balancer) giving you a degree or two. Much better than a sudden shift
of 14.

I plan on setting up the fremmel on the milling attachment of the
Myford super 7, chucking the cam in the lathe chuck, with back gear
locked, and manipulating the dremel with x,y, and z axis handwheels to
rough it out then finish it with a diamond hone. I expect to lose
about .015 to .020 lift from the original .233 and virtually double my
600-1000 rpm torque. It should pretty much self limit at just under
2500.

Generally they go the other way with those engines at the cost of engine >life. MORE rpm, with more gas, more air, and a more open exhaust, >elimination of the governor, and stronger valve springs. That is
basically stage 1. Sometimes before upgrading engine internals they
will mill the head for more compression. I've seen YouTube hotrodders
do it on a sanding belt.

Generally, instead of trying to build low end torque with a tiny engine
they built horsepower, and increased the gear ratio and they launched at >higher RPM.

Generally that's how "they" do it.
Not how "I" do it. The original had a 1.5HP engine with 8:1 cam
drive.The engine ran an atmospheric intake valve and a very
rudimentary carb. I am going to duplicate it as closely as I can

Some of the older early videos from guys like Red Beard's Garage and
Cars and Cameras from when they were still doing it mostly for fun
really do some interesting cheap mods on those small engines. Sure a
top fuel mini dragster built around an alcohol fuel turbo charged
predator 670 is entertaining, but I more enjoyed their older shorter
videos where they took an EX21 with basic mods and stretched another 5-7
mph out of it. If you must play with the 670 dropping one bonestock on
an old Paughco Springer frame was more approachable and made it more >interesting.

For reference I've got a couple Manco Intruder II carts I bought for the >kids years ago. Even with the Subaru Robin EX21 (6.5hp) they run a CVT
to an intermediate jack shaft and then a tiny gear on the jack shaft to
a giant gear on the drive axle and run only 16 inch tires. They do run >turf/sand knobbies, so take off torque is important, but I think they
are locking up at a much higher rpm than you are thinking.

When I was a kid those who were lucky enough to have an old classic 5HP
cart with a simple belt/lever friction clutch were running tiny tires.

I'm not sure an RV cam (long dureation) translates significantly to a
5HP engine, but I am more than happy to learn something. If you are >thinking high lift CAM then that is more geared towards higher RPM power.

I'm just talking. I didn't really analyze your post thoroughly.

I am moving JUST the intake valve closing event - the most critical
for low speed cyl filling to improve dynamic compression under 1800
rpm. Whet this project needs is thr EXACT OPPOSITE of what you want
for a minibike or dragster
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From Newsgroup: rec.crafts.metalworking

On Mon, 27 Jul 2026 16:33:49 -0400, Carl <carl.ijamesXX@YYverizon.net>
wrote:

On 7/27/26 11:19 AM, Clare Snyder wrote:

I am working on my Briggs and Stratton Flyer project - now at the
"motorwheel" stage. 5HP flathead 6:1 "winch engine" driving 20 inch
wheel direct drive - engine lacks bottom end torque.
I plan on advancing ONLY the intake valve closing event 14 crankshaft
degrees and getting rid of the EZ Spin decompressor bump. (the bump is
already gone - tried advancing the whole cam 14 degrees(one tooth on
52 tooth cam gear) and it ran well but loses 14 degrees of the power
stroke,( blowing it all out the exhaust) Inreased cyl filling from
advanced IVC was more than cancelled out by the short power stroke.
I plan on setting up the fremmel on the milling attachment of the
Myford super 7, chucking the cam in the lathe chuck, with back gear
locked, and manipulating the dremel with x,y, and z axis handwheels to
rough it out then finish it with a diamond hone. I expect to lose
about .015 to .020 lift from the original .233 and virtually double my
600-1000 rpm torque. It should pretty much self limit at just under
2500.

Can you grind some off the base circle and get the lost lift (and more) >back? You will have to add length to the follower region (pushrod,
bucket follower, whatever you have) to keep the geometry correct at the >valve tip, I don't know that valve train so can't help there.

There's a engine good discussion website called speedtalk.com
(unfortunately it's been fighting off bots for a week so response time
is very slow at the moment). One of the long time posters goes by >SchmidtMotorWorks, he has developed a browser-based set of software for
cam design you might take a look at if you want to evaluate your
proposed shapes. See his announcement at >https://www.speed-talk.com/forum/viewtopic.php?t=71686&view=unread#unread

Why would I want to do that? the intake valve lift is designed for
3600 rpm and is adequate to about 5000. I only need 1800, or 2200 at
the wild and raged edge.
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From Newsgroup: rec.crafts.metalworking

On Mon, 27 Jul 2026 16:33:49 -0400, Carl <carl.ijamesXX@YYverizon.net>
wrote:

On 7/27/26 11:19 AM, Clare Snyder wrote:

I am working on my Briggs and Stratton Flyer project - now at the
"motorwheel" stage. 5HP flathead 6:1 "winch engine" driving 20 inch
wheel direct drive - engine lacks bottom end torque.
I plan on advancing ONLY the intake valve closing event 14 crankshaft
degrees and getting rid of the EZ Spin decompressor bump. (the bump is
already gone - tried advancing the whole cam 14 degrees(one tooth on
52 tooth cam gear) and it ran well but loses 14 degrees of the power
stroke,( blowing it all out the exhaust) Inreased cyl filling from
advanced IVC was more than cancelled out by the short power stroke.
I plan on setting up the fremmel on the milling attachment of the
Myford super 7, chucking the cam in the lathe chuck, with back gear
locked, and manipulating the dremel with x,y, and z axis handwheels to
rough it out then finish it with a diamond hone. I expect to lose
about .015 to .020 lift from the original .233 and virtually double my
600-1000 rpm torque. It should pretty much self limit at just under
2500.

Can you grind some off the base circle and get the lost lift (and more) >back? You will have to add length to the follower region (pushrod,
bucket follower, whatever you have) to keep the geometry correct at the >valve tip, I don't know that valve train so can't help there.

There's a engine good discussion website called speedtalk.com
(unfortunately it's been fighting off bots for a week so response time
is very slow at the moment). One of the long time posters goes by >SchmidtMotorWorks, he has developed a browser-based set of software for
cam design you might take a look at if you want to evaluate your
proposed shapes. See his announcement at >https://www.speed-talk.com/forum/viewtopic.php?t=71686&view=unread#unread

The cam is ground and installed in the test engine and broken in.
runs good and obvious increase in compression when pulling the
rope.The engine has a distinct sound at low to mid rpm - a more
"authorative" exhaust note, but not the cackly one from having the
whole cam advanced (where the exhaust valve was opening with the
piston only past way through the expnsion phase of the power stroke)
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From Newsgroup: rec.crafts.metalworking

On 7/28/2026 10:07 PM, Clare Snyder wrote:

On Mon, 27 Jul 2026 14:00:52 -0400, StanWeiss <srweiss1@comcast.net>
wrote:

On 7/27/2026 11:19 AM, Clare Snyder wrote:

I am working on my Briggs and Stratton Flyer project - now at the
"motorwheel" stage. 5HP flathead 6:1 "winch engine" driving 20 inch
wheel direct drive - engine lacks bottom end torque.
I plan on advancing ONLY the intake valve closing event 14 crankshaft
degrees and getting rid of the EZ Spin decompressor bump. (the bump is
already gone - tried advancing the whole cam 14 degrees(one tooth on
52 tooth cam gear) and it ran well but loses 14 degrees of the power
stroke,( blowing it all out the exhaust) Inreased cyl filling from
advanced IVC was more than cancelled out by the short power stroke.
I plan on setting up the fremmel on the milling attachment of the
Myford super 7, chucking the cam in the lathe chuck, with back gear
locked, and manipulating the dremel with x,y, and z axis handwheels to
rough it out then finish it with a diamond hone. I expect to lose
about .015 to .020 lift from the original .233 and virtually double my
600-1000 rpm torque. It should pretty much self limit at just under
2500.

Did you ever do a cranking compression test on the engine before and
after cam phase changes?

Stan

with cam advanced it was OBVIOSLY lower cranking compression. My50
year old screw in tester does not work too well right now.

Actually the reverse should be true. You should see higher cranking compression / PSI because of the earlier IVC.

Stan
--
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From Newsgroup: rec.crafts.metalworking

On Tue, 28 Jul 2026 23:29:44 -0400, StanWeiss <srweiss1@comcast.net>
wrote:


it SHOULD have, but since all the other events were also advanced 14
degrees all the advantage if the advanced ivc went out the window.
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From Newsgroup: rec.crafts.metalworking

"Clare Snyder" wrote in message news:olcl6lhuls9i1cggmqe72ajc906n8rn60j@4ax.com...

On Tue, 28 Jul 2026 23:29:44 -0400, StanWeiss <srweiss1@comcast.net>
wrote:

it SHOULD have, but since all the other events were also advanced 14
degrees all the advantage if the advanced ivc went out the window.

Is this a moderately stressed part that could be assembled from the gear and separate lobes and bearing sleeves on keyed shafting? The lobes wouldn't
need to be hardened during testing, they and the bearing sleeves could be
slid on, Loctited and pressed together with an end bolt while you
experiment, by melting the Loctite to change timing. The lobes could be
split and overlapped to allow individual control of rise and fall timing.

If RPMs will be limited the ramp rise could be steeper and valves fully open longer than for 3600 max RPM.

See what's acceptable on this one: https://www.powertoolreplacementparts.com/briggs-stratton-592968-camshaft/?

After drawing the cam heights and shaft angles the lobe blanks could be roughed on a spin index with a plain and ball end mill and the ridges left between cuts belt-sanded smooth, first crosswise (square) down to the cut bottoms and then circumferentially for smoothness, at least on the ramps and lobe, the non contacting clearance area doesn't matter. A split experimental lobe could be the depth guide for milling a one-piece final.

Once the lobe positions are satisfactory they could be made permanent by removing the gear and passing a keyway broach through the shaft slot. Then they could be case hardened, ground or sanded smooth and polished. Keys with the hub and shaft sections offset for fine adjustment can be bought or
easily milled.

The end bolts could be cap screws with heads reduced to a narrow flange that occupies some end bearing length. I do this sort of mod enough that I made threaded bushings that fit 5C collets and run the bolt threads centered; the heads and shanks rarely are. The 3/8-16 bushing has end grooves for O rings that hold it together and was hacksawed into 3 pieces to clamp tightly on short sections of thread, the others need a locking nut.

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