# HMSK-80 valve lash spec



## ChrisJ (Nov 27, 2014)

I'm hoping some can give some input on this.
I've seen a single 0.006" in one Tecumseh manual and then another Tecumseh manual shows 0.008" and 0.012" but doesn't specify for what.

I've seen some say 0.008" to 0.012" is a range, while others say 0.008" is intake and 0.012" is exhaust.

What gives!? :smiley-confused009: :huh:


I'm thinking 0.008" for intake and 0.012" for exhaust makes the most sense but want to know what it should actually be.


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## 43128 (Feb 14, 2014)

i would just grind the stem a little bit at a time until the valve doesnt spin in the seat


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## ChrisJ (Nov 27, 2014)

43128 said:


> i would just grind the stem a little bit at a time until the valve doesnt spin in the seat



How will this compensate for when the exhaust valve gets good and hot?


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## YSHSfan (Jun 25, 2014)

I would think that using the engine numbers you should be able to narrow down the proper specs for it. Perhaps you can post the engine numbers and maybe a member can help you reseach that.


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## Grunt (Nov 11, 2013)

Page-64 shows .006 clearance for both valves on an HMSK80 motor.

http://www.barrettsmallengine.com/manual/tecumsehreference.pdf

Page-101 shows .008 clearance for both valves on an HMSK80 motor

http://www.barrettsmallengine.com/manual/tecumsehlheadmanual.pdf

I "think" I set my HM80 clearances to .008 on each valve. I guess you could set them to .007 and be in range since they allow .002 up or down from specified clearances.???


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## 43128 (Feb 14, 2014)

ive done it that way before on flatheads and it worked for me every time. if you want i would say .10


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## ChrisJ (Nov 27, 2014)

Grunt said:


> Page-64 shows .006 clearance for both valves on an HMSK80 motor.
> 
> http://www.barrettsmallengine.com/manual/tecumsehreference.pdf
> 
> ...


Hi Grunt,
I see two clearances listed on page 101 of the section manual, .008 and .012.


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## dbert (Aug 25, 2013)

I remember someone else here saying one was intake and the other was exhaust, but if you look at other items on the table they are obviously a min/max range.


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## ChrisJ (Nov 27, 2014)

I noticed Briggs and Stratton lists the following for the 1992 L head 8HP cast iron sleeve engine on my generator.

Intake : .005 / .007
Exhaust : .009 / .011


I'm thinking like has been said, 008 - 012 is a range as per the Tecumseh manual but I may try to keep the exhaust towards the larger side of that range and the intake closer to the smaller. Maybe do .008 for intake and .010 for exhaust. Obviously if the intake is already larger but within spec I'm not changing it. Will be lapping the valves for good measure before finalizing clearances.

The reason I'm doing this is, as some may remember my Tecumseh runs awesome until you work it hard blowing snow for a while, then it starts running terrible until you let it cool down for a bit, even idling for 10-15 minutes helps.

The assumption is the exhaust valve clearance is too tight.

I'll know more on Saturday.


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