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Old 10-05-2021, 10:24 AM
BillL BillL is offline
Join Date: Sep 2007
Location: Central IL
Posts: 6,518

What's all this talk about screws and washer spacing - - that is a bandaid for the shallow fins - - it only applies to aft #5 and front of #2. #6 has full fin depth on the aft side.

Randy, I have done many tricks too assist my #4 CHT being 20F higher than the rest. A couple of things might help you. 1. clean the flashing under the spark plug where the air flows through the head. Maybe 10F benefit, no serious mods to do there. Get a round file, but be warned they are hard to find. and 2. Inspect the baffle opening under that head There are two gaps. Measure them - I'll bet they are 1/4" smaller than the other heads. Pay particular attending to the gap around the CHT probes. Don't bother with the barrel gap it has no influence on the CHT. Now, this all assumes you have swapped probes to be sure it is a real head/cooling issue and not a probe variation.

Last edited by BillL : 10-05-2021 at 10:34 AM.
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