Lycoming O-360 LOP or ROP? - Pilots of America
At 75% the minimum numbers may decrease to 40 degrees LOP or 175 degrees ROP. At 65% it may be further reduced 10 degrees LOP or 80 degrees ROP. At 60% or less there usually isn't any mixture setting that'll hurt the engine, and 75% ROP is usually best power, with best economy being slightly LOP.