Vacuum Advance - Manifold or Ported

[JCoop]

Originally Posted by SuperHart

I am running a 351W with Holley carb and Mallory distributor with vacuum advance. Into what vacuum port should the vacuum advance module on the distributor be connected, ported or manifold? I have asked four different people and two say "ported" and two say "manifold". I aleady know the difference between the two ports but cannot decide which one is correct.

I went through the trouble of getting vacuum port plumbing made for the manifold on my Weber kit for the GT40. Great for the brake servo but when I hooked up the distributor advance, I got all kinds of trouble, spitting and burping at various points in the curve. I disconnected the vacuum and viola! nice and smooth. The Weber gurus said I shoulda tapped into the Webers at a particular spot as manifold vacuum WILL NOT work. Since I'm not too good with the drill, I opted to leave it disconnected and just timed it accordingly. So. I say ported.