Q: I bought a 1972 Cessna 177B with an O-360 a few months ago. It had 900 hours on the engine. My first 20 hours I would use 23 squared and pull the mixture back to 10 gph or less, then watch the cylinder head temperatures, monitoring to keep the hottest (#2) around 385°.
When the ambient temps started rising, I noticed #2 and #4 were spiking into the 420° CHT level on climb out. When I level off and set to 23 squared, I can only keep #2 below 400° by going full rich (12.5 gph) and occasionally opening the cowl flaps.
If I use 10 gph, #2 will stay around 415°. #4 will run in the 380s, and #1 and #3 will run in the 350s. [Read more…]