FYI, you can temporarily turn the Barometric Compensator (BC) into a giant mixture control knob. This can be very useful for quick experimenting. First, mark the outside of the BC so you have a reference point. You can use a marker, or if you don't want to deface it, put a piece of tape on it and mark the tape. The mark will let you carefully count turns as you screw it in and out. Note the mark's initial position, then remove BC carefully counting how many turns until is comes free. Remove and set the shims aside.
Now, screw the BC back in without the shims, carefully counting turns until it's back to it's original position. Take a short stub of hose, say 2" long and 3/4" to 1" diameter, and wedge it between the BC body and the Warm Running Device (WRD). The purpose of the hose is just to provide a little friction so the BC won't rotate on it's own.
Start up the engine, and you can now screw the BC in and out to adjust the mixture. Once you have figured out it's best position, note it based on the mark that you made. Now remove the BC again, carefully counting turns. Add or remove shims such that when reinstalled with the shims, the BC tightens up at the correct position.
This is much faster than constantly disassembling and reassembling the BC with different shims, and trying to remember whether it runs better or worse than before.
