Looks like my 12 thousandths feeler is actually 12.5. Close enough?
It's hard to see in the picture but it was pretty much centered between 12 and 13. I made sure everything was clean and used the clutch to tighten it and checked several spots.
10 was dead on so I may go with that depending on what I find.
Fullraceflathead, Thank you for the offer but part of this is I want to figure out how to do it. It's a snowblower engine so I doubt it needs to be perfect. If I somehow fail at this, or, find the valve lash is fine I have a near perfect Honda GX-200 that will get bolted on in place of the Tecumseh.