Originally Posted by dwrichey
Also thank you Jerry, I will check that out also, but I am not too optimistic because the plugs in cylinder 4 are always black compared to the other three cylinders. I'm thinking I can wrap the cylinders from the top in such a way (fiberglass cloth held in place/saturated with RTV) that will bring the one cylinder temperature up. I believe the F1 guys at Reno do something similar to improve cooling efficiency, I would just need to neck the opening down a little more.
I have my barrels (M1B 180 hp) wrapped to a 3" opening at the top, and unwrapped the 2 & 4 barrels to 5 " and there was zero change in the CHT balances. It is
helpful to wrap up to the centerline though just for air volume management. I think wraps will affect piston temps more than anything else. Nothing we currently measure.
For CHT I would suggest review of the opening gaps under the head and barrels first, closing them slightly. Edit: My gaps are the James recommended (and others) 1" lower gap and 2.25 for the heads. Then, consider wrapping on the top of the fins. Use some aluminum tape first. Might be easier to just do two heads first to compare the balance - rather than all 4 and attempt evaluation using a flight to flight differences. Too many variables.
Kinda hard to understand your low CHT's with a parallel valve engine. Easier to fix than too hot.