Originally posted by techinspector1
Moving the vacuum advance line to ported vacuum above the throttle blades will drop the advance at idle back to reality. If this is a race-only motor, you won't need vacuum advance, it's for fuel economy at high manifold vacuum (cruising).

Make a pass with it in both carb positions and without it at all. That'll tell the tale.


Since vacuum levels drop to zero or near zero at full throttle, it doesn't make any difference where vacuum is sourced from.

The dragstrip passes should be virtually identical regardless of where the vacuum can gets it's vacuum.