There's been a lot of discussion this year on the Cessna Pilot's Association
Forums about lean of peak operation in carb engines with simple
instrumentation. I've been experimenting with it and flying this way a lot.

LOP is actually easier than the "find peak and the enrich 50 - 75 degree"
method that I was taught. CHT's are no higher than running at the same power
output ROP and sometimes slightly lower.

Here is 3 meg Windows Media video file showing our O-320 H2AD being leaned
from peak to 75 LOP and then back to 25 LOP. The operation is repeated to
show the knob movement.

Note how smooth the engine sounds with carb heat on when leaned to about a
100 RPM drop. Throttle was full open and CHT were right where they are shown
20 minutes later. This video was taken at 5500 feet.

http://baldeagleflyingclub.org/LOP.wmv


--

Roger Long