Are you still chasing a rich spot in the midrange with this carb?
Just out of curiosity, how far open is the butterfly held at idle (expressed in number of turns on the idle speed screw from fully closed)? Also, is there any sort of 'half round' cut from the throttle butterfly (near where the plate meets the inner wall of carb venturi)?
Depending on answers to the above, I may have a suggestion to lean out the 'fuel curve' of the carb in the midrange.
Well, it is ever so slightly rich at just above idle, maybe around 3-3.5K rpm. It clears up fairly quickly so I'm not sure if it is just getting warmed up and still clearing its throat, so to speak. True mid range, around 5.5-6.5 K is very close. Judging from the plug color
it is just about right. That's where I fly practically everything. Throttle curve I run is a backwards and sideways ''S'' almost linear from point 0 to point 2, fairly flat curve from point 2 to point 5 and nearly linear again to point 7 which is max
There is never any need to go to full revs even in strong wind (20+). I check full revs every now and then, but only with the nose straight up to check to see how well the engine is cooling under full load. In 85 degree environment the plane can still be snapped with full authority after a vert climb of 600-700 feet, without sag. That's plenty, but we haven't had 95 degree temps yet so we'll see..... Baffling is a must and mine comes within 1/4'' of the fins
The idle speed screw was pitched long ago so to answer the second question, I really don't know. I close the thottle butterfly within 1/32'' and usually that works pretty well. I tend to run the idle mixture based on the load I'm running. For example, the 20x10.5 needed about 1/16 turn (about the blade width of the screwdriver) richer on the LS screw such that it would settle down better in flight (downlines). The 18x10 3 blader and 19x11 2 blader require a leaner idle speed.
One thing I've noticed that I haven't been able to identify cause for is the fact that inverted downlines (45s usually) the engine seems to want to rev a bit more than when upright. On the 45 down snap that works to my advantage but on the square on corner, it's a disadvantage. I suspect plumbing but not certain. The carb is not set-up for equalization and that may also be a contributor.
Does all this make sense? Did you get my earlier response?