My CH750 has a recent-production Jab 3300 with the new cylinder heads, hollow push rods, revised intake plenum, diffusers, and runners, etc. I have about 30+ hrs on the engine and continue to tweak it. My EGT's were extremely even up to about 2700 rpm and then a definite, slowly increasing bias starts with the right cylinder bank EGT's running hotter than the left as the rpm increases. I discussed this with Pete at Jabiru USA and he said a swirl in the mixture increases with rpm, favoring one cylinder bank over the other. He recommended rotating the carb a few degrees (bottom towards the "hot" side") with a goal to achieve a minimal/balanced EGT spread at 2850 rpm, which he recommended as a cruising rpm.

I arbitrarily rotated the carb as much as the distributor above it would allow ... the throttle arm extension will hit the distributor if you rotate it too much. I would estimate the rotation was probably 3-5 degrees.

I did not have "pre-rotation" numbers for 2850, but at 2800 rpm, the EGT spread was 159 degrees with a definite left/right bias. After rotating the carb, at  2800 the spread reduced to 91 degrees(also, the left/right bias is less - 2 of 3 EGT's were barely hotter on the right, and the left rear was now hotter than the right rear). Better yet, the EGT spread at 2850 was down to 68 degrees.

This seems pretty good to me (?) ... I can't rotate the carb any further without shortening the throttle arm extension and I wonder if it could get much better, anyway. Just thought this was an interesting demonstration of what rotating the carb a few degrees can do!