Tecumseh H40 re-build advise, thanks in advance

S

SAT

#1
#1
First time posting on this forum. I am a volunteer for a 501c3 non-profit. A group of folks are working on a Ken Bar Whirlwind with an original H40 engine. The aluminum cylinder walls are scored beyond repair from possible cracked ring(s). The crankcase/valve guide breather is expelling small amounts of oil mist, much more than we feel is usual. We are wanting to keep the engine in service. I have done some searching for shops that sleeve the block, but have been unsuccessful at sourcing the parts required for a complete re-build. The valve seats look kind of like they were pressed-in and we wonder if they have the meat for hone work. The valves might be salvaged, but we are unsure about the condition of the valve guides. I have read that there is a Tecumseh H40 shop manual that has specs for internal part wear amounts.
Thanks in advance for the advice and guidance,
SAT
 
markus

markus

Well-Known Member
#2
#2
I will go out on a limb and assume you are talking about a late model :small frame" H40 since you mention its on a Ken bar? To clarify though you should post the engine numbers-found on the sticker or stamped tag found at the rear lower section of the shroud below the throttle control, or possibly stamped directly to the top of the shroud in line with the head bolts (doubtful). There were 2 totally different "H40" engine designs built at different times during Tecumseh Production.
 
H

Havasu Dave

Moderator
#4
#4
And possibly clarify the purpose of using that particular engine which requires more money to repair than it's value. There are other options with which to power that bike with that would cost less.
 
creia

creia

#5
#5
Unless there is some sort of emotional connection or you are otherwise "married" to this engine you may be in for one hell of an expense to rebuild it. There are other parts that could be worn out that you did not mention- e.g., rod to crank clearance, crank to block bushing clearance, etc. Use the link provided above ^^^ and check all of the internal clearances and tolerances for "reject" size or service limit FIRST before you spend any money. My son faced this exact same scenario on an all-original 1970 Rupp-specific Hs40 last year. There was just too much worn out to make it practical to rebuild. He was patient and waited and looked around and eventually found a good used Rupp- specific short block that was in much better condition.
Michael
 
S

SAT

#7
#7
Markus, L-B Biker, HD, creia and buckeye,
Thanks for taking the time and giving the advice. We were hoping to keep the original engine with the Whirlwind being in such fine shape. We have several other projects to finish by Thanksgiving and spending lots and lots of time and money on authenticity is nice, but not really feasible.
We have a 6.5 hp Honda power plant on another mini bike and it runs great. Its easy to work on as well. So, for now, we will source another new Honda engine that is suitable for the TAV30 torque-a-verter on the Whirlwind now.
Outstanding advice and thoughtfully written all,
SAT
Edit:
Markus, here is the engine info.
Model: H40-55806A (B)
Family: TTP156U1G1EB
DOM: 8118B
Lawn-Boy Biker, I have time today read the pdf further, thanks
Havasu Dave, strictly sentimental value on the Tecumseh. We are looking closely at the Honda line of engines.
Creia, we agree.
Buckeye, the rolling stock we work on is used 10-15 times a year for parades and other public gatherings. We volunteer for the Detroit Fire Department Clown Team, a 501c3 part of the Detroit Fireman's Fund. So they are used several Thanksgiving-time parades in southeast Michigan, St.Patrick's day parades and Fireman's field day at Fort Wayne, to name a few.
Thanks for the help, nice folks here,
SAT
 
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