Vacuum advance information and myths

Dmopower said

Performance, Some cammed engines need the advance to idle well. One of my engines runs like crap without the vacuum hooked up MV and is soggy from a dead start down the road not track. Full performance should not be affected as the vacuum goes away under hard throttle.

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If that's working out, then go with it.

One issue that I've run into is particulalry noticible with an automatic transmission and a hot cam.
Manifold vacuum is fairly low, idle combustion is on the cold and diluted side, and the idle mix is somewhat leaner. When the transmission is placed in gear, the rpm drops and the vacuum drops. This caused the timing to drop, and the rpm dropped further....