Tecumseh starter rope pull back

[38racing]

Hi Again Creia

On some of these older engines, sometimes the only thing to do is to Tailor your pull to make the most of flywheel momentum. Pull the engine over slowly until you feel the piston go to TDC on the compression stroke. Now reset the starter cord and give a firm brisk pull. This will give you about 1¾ revolutions of the flywheel before the piston meets compression which is often enough to get a single cylinder engine started. Yes, you'll be pulling against a vacuum above the piston for the first ½ a revolution, but this equates to about 10 to13 psi (atmospheric pressure) against the underside of the piston which disappears as soon as the exhaust valve opens.

Non mechanically minded people seem to have a hard time grasping this concept. However, with your experience, I'm sure you'll understand the theory behind this technique. All the best,

Sky

I do all pull start that way since someone suggested it.

[creia]

Update and first observations:
I just today started to take this engine apart for some closer inspection. The bore is in excellent condition with no scoring whatsoever. You can even see most of the original factory honing "crosshatch" which suggests to me that for a 1974 engine it has had relatively low service hours.There is the usual carbon buildup on the head and around the valves which I will clean up. (I may just go ahead and do a valve job as long as it is now opened up) This is a points engine and has very good spark using a spark tester.

OK, about the valve lash: Intake= .010" Exhaust = .0145"
Tercumseh specs say .008" - .012" for both. Could this excessive exhaust valve lash be causing (or at least contributing) to the starter rope kickback problem?

This is all I have time for today. I may get the chance to pull the flywheel and look at the flywheel key and the timing tomorrow.
I welcome any and all opinions!
Thank you,
Michael

[creia]

Update # 2 and "Happy ending"!!
Today I cleaned the carbon off the cylinder head and around the valves, lapped the valves and adjusted both intake and exhaust to .010" clearance. Finally I serviced the carb and air cleaner and changed the oil and put in fresh fuel. The first thing I noticed was there was no more kickback on the starter rope! After a few pulls it fired and after some carb adjustments I have got it to idle and run pretty good. Evidently that exhaust valve being out of adjustment was causing the kickback...
Today was a good day...
Michael

[Arkie]

You got lucky.
Some days just go like that.

The Tecumseh Gods smiled on you.

When a day goes like that I want to keep working on stuff because I know things will eventually start turning wrong again.

[Skywatcher]

Hi Again Creia

The excessive lash in the exhaust valve was likely the underlying culprit. This is probably why the engine is a low hour engine, it was likely a pig to start right from new so never got used. I had a customer bring in a 3 year old rototiller with a Tecumseh engine that almost ripped hi shoulder out of its socket a few times. Both valves were close to .025" clearance, so had to really cut the seats and grind the valve faces to get the valves sitting low enough to make the ACR work properly. The next year, I had 2 snow blowers both with Tecumseh engines where the exhaust valves weren't even fully closing. The valve lash on those units were less than zero. Much easier to fix too little clearance than too much. All the best,

Sky

[creia]

Hi Again Creia
Much easier to fix too little clearance than too much. All the best,
Sky

So very true - "Been there, done that."
Michael