I'm confused on this whole vacuum port thing on the Quadrajet. From my own tuning adventures I've found that ported vacuum is always on the throttle body (base) of the carb on the passenger side. There's a little hole by the throttle blade that is covered at idle and when the throttle is opened, it is exposed to vacuum. Meanwhile, there's a port in middle of the float bowl that always gives full vacuum. Over at chevytalk.com, we've got Ignitionman screaming his brains out that ported vacuum is evil. He says full vacuum is always below the throttle blades and ported is above them. Then he says if you hook your vac advance up to ported that the more throttle or RPM, the more vacuum and advance. Maybe he's talking about a Holley or something, I don't know. Wouldn't hooking up to the port I've described be just like manifold vacuum, only not at very light throttle or idle. It is right by the throttle blade. I've ran full vacuum for my adjustable vacuum advance and it was not fun falling on my face all the time when you let off the clutch, vac falls, and some of my advance.