Setting up some of the finer points on the spacetruck project running fuel lines and such. Question is, I have two things that require vacuum, the distributor and the modulator on the trans. What vacuum is required for these item, some talk about ported vacuum whatever that is. I'm running six holley 94's and see no where for a vacuum hookup, no big deal if they both just require a line off of the manifold I'll just put some fittings in my crossover tube and that should work. Just wondering how others have setup there vacuum and if there is any thing I should know?
The tranny just needs strait vacuum, you can just tap that into the manifold. The distributor on the other hand needs ported vacuum, which needs to be tied in above the throttle plates.
The engine will idle better & be more responsive on the bottom end with full vacuum to the vacuum advance. You just need to limit it to about 10*. Ported vacuum is above the throttle blades. Full is below the blades. Tom T.
Thanks guys for the help, even though I have two conflicting answeres. No one else on here has had this scenario of there own, where do i get vacuum above the throttle plates on a 94?
Somebody has to know something about this. I know it is a little off topic being about a car related problem and all !! Maybe I should have started the post asking what kind of sunglasses greasers wear, then at least I'd get something.Tom T how do I limit the vacuum to 10* do they make a regulator or something. Maybe I'm an idiot or something usually I just hook the vacuum for the dist. to the carb, but alas nowhere to hook on a 94. I guess every one with 94's or 97's just run with no vacuum advance
Get a small piece of sheetmetal. Using the rear screw on the vacuum advance, drill a slotted hole in the sheetmetal for the screw & for an adjustment. On the other end cut out a slot. This will push up against the vacuum advance arm so make sure it has freedom of movement. Push the slot into the arm & use the screw for your adjustment. Will take a little patience, but is cheap & easy. You will limit total vacuum advance from 8*-14*. You will need a dial back timing light or mark the balancer. Tom T.
Everything I have read says to forego vacuum advance with multiple 94s. It's been said that even a single 94 doesn't produce a strong enough vacuum signal for a GM distributor .................. but I can't recall by whom. Tom's method of limiting the advance sounds pretty low-tech, but, as he said, cheap and easy. Tim D.
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