Small Engines (Lawn Mowers, etc.): valve clearance, aluminum block, service adjustments

Question
It's 11hp. The intake valve has slight clearance. My thinnest feeler will slip in but that's like a floppy piece of tin foil. The exhaust has no clearance. I'm waiting for a spring compressor to do the job. Not sure what it's supposed to be for sure. I can't seem to find a manual on 11hp L Head Tecumseh engines. I'm going to try emailing the website. I'm hoping that this is what is causing my backfire through the muffler and then I can start moving snow. Shovelling sucks.

Do you have any idea what the torque spec is for the head cover plate?

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The text above is a follow-up to ...

-----Question-----
I have a Craftsman C950-52930-0 Dual stage snowblower with a Tecumseh model #143.001103 engine. I'm quite sure it's an L head engine but there is no evidence of classification on the engine stamp. Here's a basic diagram of the head layout:

I  
   C  

E

I = Intake valve (stem down/face up)
C = Cylinder/piston
E = Exhaust valve (stem down/face up)

There should be some clearance between tappets and valve stems right? Isn't it needed to accomodate expansion as the engine heats up? It appears I have no clearance in either intake or exhaust. If so, what should I set the the clearances at? My "general repair" book says 0.08 for intake and 0.10 for exhaust. I'm having problems with exploding fuel or backfire through the exhaust.

A second question: There appears to be no nut for adjustment so would grinding down the stems be the correct method of adjustment?

Is there a routine explanation on what causes the clearances to disappear without any prior service adjustments? Any help you can give would be appreciated.
-----Answer-----
The valve stem needs to be ground to set the clearance.  A hand file usually works if the valves are not to far out of clearance.  The vavle stems do not grow/stretch.  What happens is the valve face bends slightly and the valve seats sink slightly into the aluminum block.

You do have an L head engine. What horse power is it?

As for the valves, are you measuring the clearance at top dead center (TDC) on the compression stroke?  Very important!

What are the valve clearances now?  What is the engine horse power?
Let me know.
Eric

Answer
I cross referenced your Sears number to Tecumseh engine number.

HMSK110-159961A
Use these numbers when ordering parts from your dealer.

Check out this site.  You might want to download the file.

www.cpdonline.com/692509.pdf

You will find the clearance on page 105.

.008 intake
.012 exhaust