Got valve job done, looks, feels great, compression is all good, but after about 45 seconds to a minute it starts an intermittent miss very irregular. Checked carb bowl and cut off strainer, pulled timer cleaned it looks good. Coils are rebuilt by a very recommended fellow on here, all plugs can be shorted out with screwdriver to kill that cylinder. What NEXT???
Ronnie, What engine speed is causing the intermitant miss? Idle, mid range, high speeds? Are you adjusting the carburetor (rich/lean-lean/rich)as the engine warms up to get a good setting?
Maybe a valve is too tight in a guide? That's the only thing I can think of that would cause it to miss right after starting. Does it run smooth the next time you start cold?
If the coils & timer & box are OK heat it up & find the cyl. that's missing & take compression on that cyl. If it's low (or lower) you've got a tight valve adjustment. Any popping back through the carb or tail pipe (depending on which valve it is) when the miss starts will tell you the same thing.
Watch also an air leak at the manifold - engine connection.
I tend to agree with Royce, check for a tight valve guide. Ronnie previously reported having to "knock the valve down with a block of hardwood and a deadblow hammer" and that a valve "has a very light tight spot" after working it for awhile.
If some positive action has not been taken to correct the tight valve, it could very well still be the problem.
Sounds like you have a sticky valve.
Earl's Machine Shop, Seattle, WA.
thanks guys i'll check out all the above ideas monday,tuesday gone camping