[Cliff R]

I tune for a living and don't use an AFR or vacuum gauge. We tune these engines for best results in all areas.

Idle tuning in is the easiest of all because you can simply listen to the engine as you lean up the mixture screws and hear a speed change when you just start to go lean. IF you had either a vacuum gauge or AFR gauge or both you'd see the vacuum start to fall off just a tad and the AFR start to go a little leaner.

As soon as you hear an engine speed change when turning the mixture screws in, stop, and back them up till you reach smoothest idle and/or highest RPM. This is usually about 1/2 to 3/4 turns with a Q-jet, it could be 1/8 turn with a Holley style carb.

It's always to er just a tad rich vs lean at idle, at least if you want the minimal drop in RPM's when the trans is placed in gear as mentioned above.

I'll add here that 99 times out of 100 when you see significant drop in engine RPM's when you place the trans in gear the carburetor is not the problem. It's going to be the POS spring/weight kit that someone stuffed into the distributor because someone on one of the Forums or one of their beer drinking buddies told them it would make another 100 HP over the stock parts!.......Cliff