Was running high CHT's with an O-320 B2B, rear oil cooler. Baffling tight as a duck. Used a light in a dark hangar to totally darken the upper deck. Could not climb out without going to about 420. After much research I took fobjob's idea of ramps and installed some of my own in consultation with my very cooperative IA. Also put a fence on the right one to help out by the alternator belt. Result? I climbed 5000' at Vy without going over 385 on #4. Front cylinders went up about 20, the rear down about 20. Total delta between all 4 is now 12 degrees. #3 is now the coolest cylinder followed by 4, 2 and 1. Opened up the right ramp a little bit now they all track very nicely together. I will post pictures of the ramps I built after I get them out of paint and reinstalled. This site pays for itself again! Thanks again.