Ported or manifold Vacuum to Dist.

The one thing I've found (and I haven't fooled with this in years...but if I ever get my distributor machine up and running I'll test it again) was when you are running ported vacuum advance with anything much over 230 at .050, or you are running close to the limit on CR for your combination or both, using ported vacuum you can't get the rattle out at tip in.

IOW's, when you are at a cruise and you just touch the throttle you get a rattle. I cleaned it up a bit with manifold vacuum, but wrote it off at the time that the mechanicals of the VA unit can't possible react quick enough to pull timing before you run into rattle.

At this point, I don't give up CR just to run a VA, but again, I may change my mind if I have a distributor machine here to test with, and to test full ignition systems.