Having an issue with my Carter AFB where the vacuum sucks while idling and not while accelerating. How do you stop this from happening? How do we keep it from sucking in idling position?
Get a vacuum gauge and check the vacuum ports on the carb to find one with ported vacuum instead of manifold vacuum. Then hook that port up to the distributor advance.
That's exactly how it should be - the lighter the load on the motor the more advance you get, the more economy you get - and that's just one advantage of using manifold vacuum.
When you're accelerating, your engine vacuum drops to near zero. No vacuum advance under load is what you want, and its virtually impossible to set it up any other way. Try driving around with a vacuum gauge in the passenger compartment for a while so you understand what's actually happening. Switch between manifold and ported vac to see its exactly the same except at idle. If your ported vac had a signal at idle, either your throttle is open too far and its unshrouding the port, or the bushings are shot and the throttle blade is no longer covering the hole.
Timed vacuum above the throttle plates. Manifold vacuum below the throttle plates. Which do you want? -Dave
The Jalopy Journal
