Quote Originally Posted by DennyW
In that case, warm up the engine to operating temp. Get the highest and steadiest read on the vacuum gauge you can by adjusting the idle mixture. Then, turn the distributor (with any vacuum advance dis-connected) until you reach the highest reading, and back down 2" of vacuum. This is about the best spot for the overall breathing of the engine.
I don't mind being wrong but you need to tell me what is wrong.

So basicly you are doing the same thing with a vaccum guage as I do with a tach. 2" on the lean side for you or 20 rpm to the lean per side for me. If its because I don't set each screw the same, its because each needle and seat are different. If you use a tach you will see it. This was how I was taught at automotive school. We didn't use a vaccum guage but I can understand how it works. What I'm after is the proper adjustment of the throttle plates and the idle mixture screw. After that any adjustment of the timing that effects the engines rpm can be compensated for by a small adjustment to the throttle plates. No need to adjust the idle mixture screws.