I am trying to hook up the vac advance on my distributor. Do you hook up the front port to carb or rear? Does one just vent to atmosphere? Also, I have timing set at about 27 @2500 rpm. Will I need to do any adjustment when hooking up advance?

If you have the canister with both ports hook both of them up. In '74 Porsche determined that advance was not needed and didn't hook it up. Advance is a fuel mileage / emissions thing.

Timing is done with vacuum disconnected.

Should I hook them up using a tee or put one side to each carb?

I thought the vacuum retard was for emissions.

I think the previous answers may have missed the fact that you have a carb. (Or hopefully two; duals are far preferable than the single-carb setup.)

The fitting on the vacuum thingie (the dashpot) that points back toward the distributor body is the retard fitting. The one pointing away from the distributor body is the advance fitting.

You hook the retard line to a place on the carb that has vacuum at idle. That would be somewhere below the throttle plate.

You hook the advance up to something that has vacuum only when the throttle is very very very slightly open. That would be somewhere just above the closed position of the throttle plate.

If your carb doesn't have one or the other (or both) then just don't hook up that fitting.

--DD

OK i think I have the retard one hooked up correctly but I'm not sure where to hook up the advance. Do you have a pic of those spots? By hooking up just one if I only have one available do I gain anything?