RE; vac advance. I have always run ported vac on mine. I once tried manifold vac and it ran terribly. Couldn't get the idle below about 1100 because of the extra advance. So I went back to ported. But that was prior to discovering that I had that super max amount of vac advance. I understand the theory of running manifold vac but it's just not worth it to me to screw around w/ it now as I am extremely happy w/ how my engine runs.