anybody make high performance parts for a tecumseh

H

Havasu Dave

Moderator
#12
#12
Hey guys, what is the advantage of using billet, or 5.5 rod with these HS motors? Where are the isky cams producing power? Reason I ask, is that we're still stuck with the flywheels.
It would be neat if we could build a sleeper Tec on an old bike, that retained the original look to it. :shrug:
 
ole4

ole4

#13
#13
I am not sure that there is no billet flywheel that will bolt on to a tec. HS50 or hs40. I remember asking ARC about a Billet rod and they said they did not have one. Someone here took the time to measure and find out that the 5.5 rod had the same dimensions. The dipper was slightly different but it worked fine. I had used that rod for a few years now and it works great. After I finish my Rupp project, (if the cold ever leaves) I am going to remove my HS50 flywheel and measure the taper angle and inside flywheel ID and outside ID and see if ARC has anything In the tec diameter and taper that fits. My tec is the later one with the CDI on the outside of the flywheel. If you have one with points and inside magneto I think you would be out of luck. Have to see if the tec CDI would fire with the ARC magnet arrangement and if no fit a Honda or clone coil to it.
 
H

Havasu Dave

Moderator
#14
#14
ole4 said:
I am not sure that there is no billet flywheel that will bolt on to a tec. HS50 or hs40. I remember asking ARC about a Billet rod and they said they did not have one. Someone here took the time to measure and find out that the 5.5 rod had the same dimensions. The dipper was slightly different but it worked fine. I had used that rod for a few years now and it works great. After I finish my Rupp project, (if the cold ever leaves) I am going to remove my HS50 flywheel and measure the taper angle and inside flywheel ID and outside ID and see if ARC has anything In the tec diameter and taper that fits. My tec is the later one with the CDI on the outside of the flywheel. If you have one with points and inside magneto I think you would be out of luck. Have to see if the tec CDI would fire with the ARC magnet arrangement and if no fit a Honda or clone coil to it.
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Ole, thanks for the response. I've been following these Tec threads with interest.

I was thinking that it would be better (tuning wise) to use the points setup, because we could easily mess with timing advance, as opposed to living with preset mag location, or an offset key.

I was thinking more sleeper motor, than outright race motor, even using Tec carb. Just getting more grunt out of a stock looking early 70's motor.

We see the threads and photos of clone engines with flywheel shrapnel, but what about the FH Tecs? How many RPM will they take, and is that "limit" within the cam specs?

LOL, looking at the head and valve threads, some of you guys'd have no problem turning down a wheel to fit.
 
roccosbike

roccosbike

#15
#15
If you get your hands on the newer Tecumseh that uses the coil outside the flywheel like a briggs,you can have a billet flywheel tapered to work on it and even use a PVL coil. If your running a mikuni style carb then your gov is not hooked up any more and you will loose the stock con rod ask me how i know.So if you dont want a hole in your block from the stock con rod then the billet is the way to go.
 
The Restore Kid

The Restore Kid

New Member
#16
#16
ole4 said:
I am not sure that there is no billet flywheel that will bolt on to a tec. HS50 or hs40. I remember asking ARC about a Billet rod and they said they did not have one. Someone here took the time to measure and find out that the 5.5 rod had the same dimensions. The dipper was slightly different but it worked fine. I had used that rod for a few years now and it works great. After I finish my Rupp project, (if the cold ever leaves) I am going to remove my HS50 flywheel and measure the taper angle and inside flywheel ID and outside ID and see if ARC has anything In the tec diameter and taper that fits. My tec is the later one with the CDI on the outside of the flywheel. If you have one with points and inside magneto I think you would be out of luck. Have to see if the tec CDI would fire with the ARC magnet arrangement and if no fit a Honda or clone coil to it.
Click to expand...
There are different tapers to all the cranks.. I have an HS50 ball bearing points crank with the real big taper.. can't even use it because I have no flywheel for it...

BUT NO MATTER TAPER, you gotta get the right one... You can have an H50 crank, and HS50 crank, both with the same taper, but ya try to put an H flywheel on the HS.. the DEPTH is different.. The depth from the magnets to the taper is different...

An H flywheel would crash into the block before ever finding the crank.. HS would stick up off the engine an inch...

Ya know what i mean?? Crank shaft taper LENGTH varies on them too... where it lands in correlation to the world..

I guess if you are using the briggs wheel with an EIC motor you could just change the length of the mounting studs to make them align
..

.
.
also, all EIC blocks still have mounting studs and parts for an older coil.. Studs are not tapped, but tap the holes and it is a magneto motor..
 
MB165

MB165

Active Member
#17
#17
I emailed tim regarding a cam for the HS40 last week. havent heard back yet, but what I figured for my Rupp build was to keep the lighting flywheel, and just make a cam profile for lower RPMs, up to around 4000rpms. Not a real radical lobe..... It might not even be worth modifying it depending on what he says he can do with it..:shrug:.
 
roccosbike

roccosbike

#18
#18
MB165 said:
I emailed tim regarding a cam for the HS40 last week. havent heard back yet, but what I figured for my Rupp build was to keep the lighting flywheel, and just make a cam profile for lower RPMs, up to around 4000rpms. Not a real radical lobe..... It might not even be worth modifying it depending on what he says he can do with it..:shrug:.
Click to expand...
Once you disconnect the gov your going to get that many RPM's no problem.When i was kid we used to disconnect the gov remove the head gasket and run em like that on our go karts.I can't tell you how many of them i put the rod through the block but they would spin quite a bit of RPM's before it would happen.Back in the 70's i could get those motors for next to nuthing all day long.
 
joshua. c.

joshua. c.

Well-Known Member
#19
#19
just to warn you i got 3 cams done by isky recently they came out with pit marks in the cam faces. i got upset and contaced dyno cams for a second opinion. both isky and dyno cams sed its a problem with the tecumseh castings but they will run fine. both sorces sed it happens to most re ground tecumseh cams. and they sed briggs cams dont get marks due to a different type of casting. so if you get your tecumseh cam re ground don't freek out if it comes back with pit marks, its normal.
 
H

Havasu Dave

Moderator
#20
#20
joshua. c. said:
just to warn you i got 3 cams done by isky recently they came out with pit marks in the cam faces. i got upset and contaced dyno cams for a second opinion. both isky and dyno cams sed its a problem with the tecumseh castings but they will run fine. both sorces sed it happens to most re ground tecumseh cams. and they sed briggs cams dont get marks due to a different type of casting. so if you get your tecumseh cam re ground don't freek out if it comes back with pit marks, its normal.
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Thanks for the heads of Joshua.

I just heard back from Tim on the HS40 cam. .275" lift and 230 duration @ .050" on a 104 degree lobe separation angle that would give great torque right off idle and pull to 5 or 6 grand depending on carburetor size, port size, and valve size.

I used the dremel and got the chunks of casting out, then lapped the valves. Bore was a smooth 2.6 but ring gap was 035, so I'll tighten them up with new rings.

Just trying to get a stock appearing motor to run a lot better. Not build a race bike.
 
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