Cliff,
On each Quadrajet I've ever seen, the vacuum ports all have a letter designation, but nowhere have I found a chart or list of what each of these is typically used for.
Of course some are obvious, such as the PCV, brake booster, choke pull-off, but some are not always easily identified.
What I mean is, which one would typically be used for the EGR, or the emissions vapor canister, (and that could have 2, one for the control, and the other for the evacuation). And then there's the vacuum advance which can be either manifold vacuum or ported.
Is there any such chart or list of port functions on the Quadrajet?
I'm trying to figure out which port i can use for the emissions vapor canister. On my 88 Burb with the original TBI, it had a line coming from the canister to the TBI which was connected to a port that didn't apply vacuum until the throttle was opened slightly, and it didn't apply much. The port split internally and went to each side.
When i did the swap to the Quadrajet, initially I used an older vapor canister that had multiple lines, one of which was a control, another was the suction.
In the interest of simplicity, I went back to the original vapor canister which has just 2 ports,one from the gas tank, the other to the engine.
I think that port "K" on the front of the base plate is the one that should work for this, but I'm not sure it applies enough vacuum for the canister to evacuate properly.
I want to use the canister to keep the fumes down, and to avoid any fire dangers, (plus it keeps the wife from complaining about the smell).
The other one I'd like to know is the vacuum advance. I've seen port "H" used for this, but I've also seen this port use either manifold vacuum or ported vacuum. My question concerning this is, does it just matter what the original application was for any given carburetor as to which vacuum this port applies, or are these all supposed to be the same from carb to carb?
I know, a complicated question, but I figured if anyone would know, you would.
Thanks in advance, Rick
The port designations I've seen are these:
A,B, T, K, H, G, F, D, V, N, L, but I've never noticed a C.
