Toastintx

ok heres the question. do i use timed vacuum for the distributor or manifold vacuum. i heard or read both what do i do and what makes a difference.
Thanks
Johnny

oxfordbp

You are supposed to use timed vacuum, people who use full vacuum do so for performance reasons. Manifold vacuum will basically advance (OR retard I cant remember) the timing so you get a small boost in performance. I dont run any vacuum and run off the weights in the disty.

If your motor is stock or very mild I suggest timed vac.

jlg2002

The vacuum cylinder on the dist. is hooked to the breaker plate which rotates in advance. You do not want this much advance at idle due to spark knock (detonation) issues on pump gas. Hooking to straight manifold vacumn will perform this rotation. Therfore, you want carb vacumn applied to the dist so that the advance is brought in gradually as the carb butterflies open.

Firstgothenshow

Timed vacuum for timing on a distributor via a vacuum advance unit