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I had a lot of issues with high CHTs and what really helped bring mine down was opening up the air outlet on the bottom of the cowling as was suggested by other builders on here.

Night and day difference. My cylinder temps dropped substantially after doing that.

We already have a gigantic outlet. Not sure what the dimensions are but it's large.

First thing is to make sure your engine baffles are 100% sealed to the engine. Use a light on top, close your hanger doors so its dark inside, and watch from underneath as someone moves the light around on top. Any gaps or openings will be easily spotted and you can seal them up with some high temperature RTV. There will probably be areas you can not reach with the caulking tube. I added a 1' piece of 1/4" ID tubing to the end to get to these areas. Now pay attention to the rubber cowling baffles. Make sure they make 100% contact with the cowling with no gaps. Check engine timing. CHT temps are generally higher until they get broken in and the rings are seated on a Lycoming. I would expect the same with your engine.

9GT wrote:close your hanger doors

Hanger!?!? I wish!