advance/ported vacuum questions

[txchainsawgogi]

i just want to double check on where all the carb's hoses should connect. 1978 chevy 350 5.7L V8. the carb is a 78 rochester qjet 4MV. All of the emissions stuff is gone.

i have the vacuum advance on the distributor hooked up with a T connector to a port on the side of the carb by the choke and also to the front of the carb (the smaller port above the right idle mixture screw, not the large port under the fuel inlet).

[1979C20]

What components do you still have on your truck? Egr, vac adv, pcv? For the vac advanve, if you want it on full vacuum, start the truck and put your finger over the hole to see if it draws vacuum at idle.

[txchainsawgogi]

no emissions, no egr. vacuum advance and thats it.

[txchainsawgogi]

does this port need to be hooked up to anything? the idle seems to run smoother with it plugged.

its on the passenger side of the carb, under the choke pull off.

[txchainsawgogi]

i really need help identifying this port... its really bothering me that i cant find it in the manual! does this port need to be hooked up to ANYTHING? it was previously T'd to the vacuum advance but i realized it probably shouldnt be. should i connect it to the same post on the manifold the trans modulator is connected to?

[1979C20]

Okay, if you removed all of your vacuum lines except your vacuum advance, then plug all the others that arent being used. Thats what I did.

[VileZambonie]

Originally it was timed. Hook your vacuum advance and your choke break to manifold vacuum.

[txchainsawgogi]

Originally it was timed. Hook your vacuum advance and your choke break to manifold vacuum.

What about the port in front, above the right(driver's side) idle mixture screw? What do I hook that up to?

[1979C20]

You plug it. Thats a port to hook vacuum controlled parts to. It draws vacuum into the carb, nothing draws on it.

[txchainsawgogi]

im confused. the vacuum advance on the distributor should be hooked to MANIFOLD vacuum? so then do i just plug it to the port under the choke pull off on the carb since it sucks in at idle? or do i need to plug the vacuum advance, and the carb's port into the intake manifold, where the transmission modulator connects?

the timed vacuum source(in FRONT of the carb, ABOVE the idle mixture screws) essentially does nothing for my set up?

[VileZambonie]

Any port on the carburetor that has a vacuum signal at idle is manifold vacuum. A ported vacuum signal only receives vacuum when the throttle is open. A timed vacuum circuit utilizes a thermostatic vacuum switching valve or an electronic solenoid. Venturi vacuum you need not worry about.