Thanks Kent. What I would give to have one-tenth of your knowledge…
I’ve been chasing this rabbit ever since I bought the Long EZ in February. I thought I had it fixed by patching all the rips and holes in the silicone baffle seals and orienting the seals correctly. With that, I’ve run the engine with a leaf blower aimed in the NACA and CHTs do not rise above 400. Without the leaf blower, CHTs rapidly rise to ~450.
My high CHT issue is isolated to #4 (although #3 runs in the upper 300s). #1 and #2 are in the lower 300s.
Take a look at the attached pics. I have up-draft cooling with no air diffuser from the NACA and the carb air inlet with no filter oriented below the #4 cylinder. I think this off-set orientation plus my carb heat SCAT, is blocking airflow from reaching the #4. I hope by moving the air inlet and SCAT, this will allow air to more freely flow to the #4 (similar to your set-up).
I spoke with the folks at Vans this afternoon and have purchased one of their filtered air boxes. It’s for a 320 so I’ll have to modify it to fit the 235. While I’m waiting for the air box, I’m going to test the CHT sender.
Thanks you your input.