You said the ported vacuum was not pulling the advance plate around like it should? This is on a rebuilt 2150,,, did you check the base for a warp? what kind of gasket are you using,,, thin,,, or thick,, has this gasket got the cut out for the ported vacuum port? some times the base is just warped enough to leak by vacuum when using the single thin gasket, sometimes this can be fixed by using the thicker base gasket. some kits come with 2 thin gaskets. One is used on the manifold under a spacer and the other is used under the carb on top of the base, these 2 gaskets are different. These carbs were used on several manufactures and models of vehicles and the applications and variations of the kits are 100's make sure all parts and gaskets are identicle to your application.