Top Overhaul VS Major Overhaul?

[cfiatzph]

Also I had poor experience with unison plugs so bad that we swapped them out after about 25 hrs. The a/c had (a 0-200) had milleniums on it and about 400 hours and compression all in the 70's. These plugs would basically lead foul like crazy.

[CBogle]

Dave:

After starting at full-rich, I pull the mixture almost all the way back to the point where if I lean any further, it runs rough. I never exceed 1000 rpm in this leaned situation during taxi so I don't believe the engine can be harmed in any way.

Just before run-up, I go full-rich, perform the run-up mag checks and carb-heat, then take-off.

After landing, I lean again for taxi back to the hangar.

So far, no fouling using this procedure.

Curt

[blueldr]

A too lean mixture will not harm an engine at under approximately 75% of maximum power. If you lean the mixture in cruise at about 65%, you
can lean it down to where it runs rough as hell and the temperatures will still not get into the range that will do engine dammage. Of course the power will fall off to where the air speed goes all to hell, but it wont hurt the engine.