+1 Wrenchbender. I run Holleys and there is a Timed Port and a full Vacuum port (Lowest port on the carb at the base) I was having trouble with starting and long warm ups. Drag Racer friend suggested going to full vacuum port for vacuum advance.
Tried it on a 383 stroker and a 400 poncho. Easy starts and doens'nt seem to hurt performance. I have heard that doing this will acutally retard timing at higher RPM's. Have not noticed this as if yet. Some tuning will be required if you do this,
