Carburetor replacement - extra inlets, vacuum?

[Reese Allen]

1980 C20, small block 350 V8, had a 4-barrel Quadrajet 17080201 on it previously. I've owned it since 2012. Previous owners put a crate motor in it in 2000. No idea whether they replaced the carb.

I bought a UREMCO 3-3622 rebuilt carb to put on my truck and it's different from the old carb in a couple of ways.

First is in back, where the actuator at the rear passenger side was connected directly to a nipple nearby on the back of the carb body with a hose before, this one has a tee in the middle. I suppose I am supposed to plumb this to the nipple coming up out of the intake manifold a couple of inches away which presumably pulls a vacuum.

Second is in front, driver's side, there's an extra nipple on the new one. Old carb has nothing there at all.

I figure I should just plumb both to vacuum from the intake manifold, but figured I should ask before I go ahead with it.

Photos attached.

[geezer#99]

Negatory on the back one. It’s already manifold vacuum. Likely another hose went to the aircleaner. You could just use a hose like your old one.
What aircleaner you got?
On the front that’s ported vacuum source. Ported vac is sourced above the throttle plate. Shows no vacuum until The plate opens.
Cap it or use it for your vac advance on the distributor.

[Reese Allen]

Thank you. A friend of mine also tells me that both can just be capped.

I don't know what the air cleaner is. It's got a big Edelbrock logo on top. AFAIK the only thing it's supposed to be plumbed to other than the intake manifold is a big hose coming out of one of the valve covers. The hose doesn't reach so I just have it taped off on the air cleaner and the hose is venting to atmosphere. Separate problem.

[geezer#99]

You’ll need that fitting on the back by the tee’d hose swapped over to your new carb. It’s for the brake booster vacuum line.
What trans you got?

[geezer#99]

The big hose is for filtered air from your aircleaner. That hose will supply fresh air into your motor to mix with crankcase fumes and be pulled out by your pcv valve.

[Reese Allen]

Originally Posted by geezer#99

You’ll need that fitting on the back by the tee’d hose swapped over to your new carb. It’s for the brake booster vacuum line.
What trans you got?

Good catch, I wouldn't have noticed it was missing until I had the new carb 99% installed.

It's four on the floor with the granny gear.

[geezer#99]

Good chance your carb was original.
I noticed the missing linkage arm on the drivers side.
You’ll see what I mean in this link. There’s a couple pics right away show the difference.
Your new carb came from an automatic tranny vehicle. It shows the kick down hook up like in the link.
Your motor won’t know the difference.

http://www.crankshaftcoalition.com/w...4MV_carburetor

[geezer#99]

Your carb number comes up as a 1980 model.
Keep it. Might be you want to use it for a numbers matching build.

[Reese Allen]

New carb on, truck runs pretty good. Thanks geezer#99.