Quote Originally Posted by tcodi
I just put in a summit hei distributor and set it up with the vacuum plugged and set the baseline to around 12. When I hooked the vacuum up to the full manifold port on my carb it went up to almost 40 degrees.
The idle ran great like that, but is this too much? Is the vacuum can supposed to put that much advance on it?

I also tried using the timed vacuum port and in that case at idle it didn't do much but if I cracked the throttle at all it would jump up to about the same point. Will I hurt anything by running this much vacuum advance if I use the manifold port?
i've run it both ways, according to what i wanted it to do. if you leave it ported then you can pull your base timing lower (5 degrees) for better starts. ported vac. retards the timing when you crack the throttle and the timed vac., adv. the timing when you crack the throttle. i'd try it both ways and see which one works better. someone will come along and say you can't do that, but they are wrong.