Tecumseh H50 Stroker

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OND

#81
#81
delray , you are correct the .060 is no good and I was thinking and maybe hoping I can find a longer lifter. The lifter stems are 5/16 diameter just like the stock valves stems were. I've done some checking on the Briggs 5/16 Lifters that are made by ARC and they are actually shorter in length than my stock Tec lifters …..so that's a no go ! I'm hoping to find a Tec lifter that I can cut down .
As far as the dual valve springs I'm pretty sure they are going to be to short in length . I mostly wanted the retainers , locks and spring guides …$25.00 and I'll save the springs for something else . Don't have any numbers in front of me at the moment because I left them in the shop. Hoping the spring kit will be here before the weekend , and I'll post some better numbers.
Are the motorsport lifters 1/4'' or 5/16'' in stem diameter ?
 
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#82
#82
Dr. Shop Teacher said:
Re Delray's comments--the big block lifter is massive in diameter (more than 0.34)--and is the same through the HM100. HM80 lifters may be long enough to be cut down, though the stroke would indicate otherwise. NOS H60 valves in can be found for about $10 each on eBay, if that becomes necessary
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Thanks Pete ….you don't happen to have an H60 or H70 lifter that you could measure for me ? I'm thinking they are all the same though. Reason I'm going with the Briggs valves was the smaller stem size for a little better flow and there easy to find better retainers and locks for .
 
delray

delray

Well-Known Member
#86
#86
here you go OND.
I had two different sets that a got from a gentleman that work for Tecumseh(straight from the plant here in wis)
the first set are about 2inch long ,just .004 under that. other set are 2.075 and the thickness is about .310 (about 5/16)




might be just better off going with a stock valve. I don't think your going to get a real advantage with the narrow stem valves with a cam that's only going to spin 4500+ rpm's
maybe just try to concentrate on getting the correct springs with stock valve length and still use the good retainers/keepers.
reasons I say that is the motor doesn't have any real good parts in it to rev it above 4500+
still using the old style piston with the thick rings and aluminum bore,heavy flywheel,stock ignition. also still think you will be very happy how well
the engine will run even with just couple good mod's done to it. good header and a mikuni will be a big plus too......
 
markus

markus

Well-Known Member
#87
#87
These are the numbers listed for the SBH/motorsports H50's optional lifters. Of course finding some may be an issue but someone might have some in stock....

Tecumseh 36884K
Valve Lifter (Intermediate)

Tecumseh 36607K
Valve Lifter (Longest)


There is also the option of adding material to the tip of the valve, I had some like that from I believe wiseco when I bought out a parts lot of NOS small frame H and HS performance parts a couple of years ago. Bottom right on the photo below if it shows up (from an article showing the build up of a Yellowjacket engine from Rons cycle city back in the 70's

 
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OND

#88
#88
delray said:
here you go OND.
I had two different sets that a got from a gentleman that work for Tecumseh(straight from the plant here in wis)
the first set are about 2inch long ,just .004 under that. other set are 2.075 and the thickness is about .310 (about 5/16)




might be just better off going with a stock valve. I don't think your going to get a real advantage with the narrow stem valves with a cam that's only going to spin 4500+ rpm's
maybe just try to concentrate on getting the correct springs with stock valve length and still use the good retainers/keepers.
reasons I say that is the motor doesn't have any real good parts in it to rev it above 4500+
still using the old style piston with the thick rings and aluminum bore,heavy flywheel,stock ignition. also still think you will be very happy how well
the engine will run even with just couple good mod's done to it. good header and a mikuni will be a big plus too......
Click to expand...
Thanks delray for checking out your lifter supply and I'll measure mine tomorrow , seems like they were longer than 2'' though .
Yea this engine might not spin much more than 4500 r's , just want a good , dependable big block . Oh and this engine is a steel sleeve block.
 
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#89
#89
markus said:
These are the numbers listed for the SBH/motorsports H50's optional lifters. Of course finding some may be an issue but someone might have some in stock....

Tecumseh 36884K
Valve Lifter (Intermediate)

Tecumseh 36607K
Valve Lifter (Longest)


There is also the option of adding material to the tip of the valve, I had some like that from I believe wiseco when I bought out a parts lot of NOS small frame H and HS performance parts a couple of years ago. Bottom right on the photo below if it shows up (from an article showing the build up of a Yellowjacket engine from Rons cycle city back in the 70's
Click to expand...
Thanks markus , and yes I've thought about welding the valve stems . Love the Yellow Jacket and the Smokstak Tecumseh builds !


https://www.smokstak.com/
 
delray

delray

Well-Known Member
#92
#92
OND said:
Thanks delray for checking out your lifter supply and I'll measure mine tomorrow , seems like they were longer than 2'' though .
Yea this engine might not spin much more than 4500 r's , just want a good , dependable big block . Oh and this engine is a steel sleeve block.
Click to expand...
cool....
that's a plus for sure. when it comes to performance and long liability you really can't beat a steel sleeve engine. I ran a steel sleeve in my ohh-race motor this summer and was turning over 8200 rpm's and on a very hot day and the sleeve doesn't even look like I ran the engine.
 
S

stuart egli

New Member
#95
#95
I'd be interested in one of those rods. I'm building an H60 like I used to race in my minibike back in 1970.

Most of our engine work was done by Ernie Bose (of Quarter Midget engine building fame) The extra .25 in of stroke in the H60 vs the H50 made for a significant performance advantage. Ernie Bose machined oversized valves starting from GM valves. The were so big in dia that they almost touched. Initially both valves were the same size. Our best combination was when we biased it towards the largest possible intake valve. We ran methanol with 25-40% nitro. Ernie also ground our cams and valve springs. Ernie's philosophy was to run light valve spring and float the valves at high RPMs!! It worked...
 
delray

delray

Well-Known Member
#97
#97
stuart egli said:
We used to run the flywheel off of a 3 hp Teke on our H60s back in early 70s. If there were any mods needed they were minimal. Planning to do that on my current project.
Click to expand...
I had no problems running a stock aluminum hs-40 on my small block this summer at 7000+ rpms. maybe one of my smoothest revving motors I ever had.
https://www.oldminibikes.com/forum/index.php?threads/hs-40-build.161335/

I am assuming the Hblocks have the same tapper shaft as the small blocks do.(points engines)
 
delray

delray

Well-Known Member
#98
#98
stuart egli said:
I'd be interested in one of those rods. I'm building an H60 like I used to race in my minibike back in 1970.

Most of our engine work was done by Ernie Bose (of Quarter Midget engine building fame) The extra .25 in of stroke in the H60 vs the H50 made for a significant performance advantage. Ernie Bose machined oversized valves starting from GM valves. The were so big in dia that they almost touched. Initially both valves were the same size. Our best combination was when we biased it towards the largest possible intake valve. We ran methanol with 25-40% nitro. Ernie also ground our cams and valve springs. Ernie's philosophy was to run light valve spring and float the valves at high RPMs!! It worked...
Click to expand...
kind of like having a rev limited built in...….
 
markus

markus

Well-Known Member
#99
#99
These are the numbers listed for the SBH/motorsports H50's optional lifters. Of course finding some may be an issue but someone might have some in stock....

Tecumseh 36884K
Valve Lifter (Intermediate)

Tecumseh 36607K
Valve Lifter (Longest)
delray said:


crazy how they did things back in the day. just weld material to the top of the valve and regrind it to fit. hey it works.
Click to expand...

Yea, I guess they took a lot of material off the reground cams back then. Nowadays with the Tec Motorsports and Dyno cams its the other way around (of course those were intended for an OHV and not flatheads to begin with)

I dug one of the modified ones I have left out of that parts purchase and compared it to a stock one. Its an intake valve for a small frame H, I had the exhaust valve too but someone picked that one up from me (that crossed with the HS engines) I think someone was gonna build an H30 as I got an .080 over wiseco piston for one in that parts buy. Would have been neat to get the modded cam!

IMG_0505.JPG
 
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#100
#100
delray , I just went out to the shop and measured one of my lifters and it measures 1.918 and is about .310 diameter on the stem . If you want to sell a set of those lifters you have send me a pm .
 
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