Originally Posted by
Flamin_Squirrel
Eh? If you lean past peak, CHTs will get cooler not hotter, so that statement requires a qualification for it to make sense.
As a general rule it is impossible to get a carburated engine like you find on the vast majority is trainers/simple tourers, to run smoothly at lean of peak mixture settings because of the inherent uneven fuel distribution between cylinders.
But full rich mixture will deliver more fuel than can be burned, the excess will carry away heat and thus reduce CHT's. Leaning will eliminate most of the "extra" fuel thus loosing the cooling effect and causing a rise, and sometimes a dangerous rise, in CHT's.
I want to emphasize that I am taking about
aircraft in common use. That is single engine fixed gear Piper and Cessna aircraft manufactured in the 1970's and early 1980's. I am sure someone can find some obscure aircraft with exactly 13.5 airframes in existence where the above comment does not apply but for aircraft that average reader of this forum has even seen let alone flown, I believe my statement in post number 28 is accurate.