[Jim Harchanko]

My O-360 has 400 hours SMOH. On several occasions I have received reports of a puff of engine exhaust smoke occurring at touchdown or as I turn off the runway. Compression is approximately 79/80 on all cylinders. There is an oil leak from the front seal but otherwise oil consumption is well within limits (quart per 6 to 8 hours). Sided movement of the valves on cylinder #1 were noticeable but not having the jigs, I did not measure the amount of movement per Lycoming Service Bulletin 388C. I'm guessing that my valve guides may be worn and that this is the cause of the smoke. I'm currently thinking that a jigs can be fabricated to measure side movement of the valve per 388C. Has anyone else experienced this or have insights on the cause of smoke puffs?

 

[dhammer]

Smoke

The other source of smoke may be the fuel. I believe gray is usually oil and fuel is black. Maybe with the throttle back and mixture rich it's loading up and puffing as RPM's are coming down on landing. Just a guess.
Don