Use or don't use vacuum advance on distributor???????????????????
My car Runs Great for me.
This is really what it's all about. The worlds full of individuals. Some owners don't know, some don't care, some are very happy as it is... All that's really important is the owner is satisfied. For me, that means running one.
The last time I checked one, which admittedl was years ago, the stock vacuum can started being affected at 7-8" of vaccum.
You can adjust it by sticking an 11/32 allen wrench down the vacuum nippled on the distributor can, but all you're doing is adjusting the amount of vacuum it takes to move it. Not the amount of degrees of advance.
Crane used to offer a performance curve kit for small blocks with a vacuum can that was better with lower vacuum levels. I bought the last 3 I saw on Ebay a few years ago but every once in a while once shows up.
The only difference between ported and manifold vacuum source is the advance at idle. Ported does not allow for the vacuum pod to affect initial timing. Manifold does. Otherwise - they do the same things, at the same times. The way it was taught to me this was to prevent the timing from bouncing around if the idle vacuum was unsteady. It had nothing to do with hydrocarbons or convertors because as I said, at the time they were added, nobody gave a rats *** about emissions - even in CA. Some manufacturers were wary of erratic idle, and some weren't. I think it was Ford that had both vacuum advance and retard in the same dashpot that was controlled by a temperature controlled vacuum switch and the throttle position.
