quadrajet question

[Buddy]

just took the Holley off my truck and put a quad on. Now my question is where do the vacuum lines all go. I have only 3 vacuum lines to go on. I know one goes to the booster, this one is on the back, one goes to the PCV this on is on the front. Know I know one comes of the vacuum advance! there are a few spots this could go on this carb, not sure which one to use. Also When I disconnect the vacuum advance is there supposed to be vacuum coming from the line that goes to the distributor, or does the vacuum come from the carb and go to the advance that way? Also I cant seem to get the secondaries to open! do these work off the vacuum ? Also on the vacuum side of the carb ,beside the choke their is another small vacuum looking thing. This looks like it is supposed to have a small vacuum line running from it to the carb , about 3" long line ,this is not there should it be there?

[eventhorizon66]

The port on the front of the carb on the lower driver side corner is the "timed" vacuum advance port.  The vacuum from the carburetor pulls on a diaphram inside the vacuum advance canister and advances the timing under high vacuum conditions.

The small "vacuum looking thing" near the choke is the choke pulloff.  It opens the choke a bit when the engine is running and also holds the secondary air flap shut under high vacuum conditions.  Yes it is supposed to have a short piece of vacuum line connecting it to the port that is pointing towards the pulloff canister at an angle.

When you say you can't seem to get the secondaries to open are you refering to the air flap or the throttle blades in the carb base.  There is a little lever on the passenger side of the carb base plate that prevents the secondary throttle blades from opening until the choke is fully open.  As far as the air flap, that only opens when the engine demands it.  So it won't fly open when you blip the throttle in neutral.

http://www.youtube.com/watch?v=nRK9n4NQvOA

[Buddy]

just want to double check what you said. The vacuum adavnce air vacuum line goes to the small inlet on the DRIVERS side not the passenager side correct! if this is true do i plug the one on the pass side? I have the truck running good now, however i cant take it for a drive to be 100% sure. saying that I cant get my seconadry butterfliies on top of the carb t0o open even when i hold the choke wide open. am i doing something wrong there.

[eventhorizon66]

There were quite a few different vacuum port variations for the q-jets over the years.  It might be best if you could post a pic of your Q-jet so I can be sure we are talking about the same thing.  But for a mid-70's to early-80's non electronic Q-jets, the distributor vacuum advance goes to the small vacuum port on the front lower driver side of the main body (to the right of the filter housing if you are looking at the front of the carb).  This will be your "high signal" timed vacuum there is also a port just above the fuel filter housing that should be the "low signal" timed vacuum port for things such as EGR.  Confirm this by putting a vacuum gauge on each of these ports and opening the throttle slightly.  One will have a signficantly higher vacuum reading.  That's the one you want for the dist. advance.  Just in case you don't know "timed" means that it only provides vacuum when the throttle is slightly open.

Plug any vacuum ports not in use.

What is on top of the carb on the secondary side is not the butterflies, but the air flap or air valve.  Do you mean you cannot manually open it by hand or it will not open when you pull the throttle open.  Like I said when the engine is running it should open only when the engine demands the additional airflow.  But if you cannot open it manually, there is a problem.

[Buddy]

I will try to post a pic later noight. As for open the flaps on the top they will open by hand they just dont open when i gun it in the garage

[eventhorizon66]

This is the port I'm talking about for your vacuum advance:
http://www.highperformancepontiac.com/tech/vacuum_advance_tech/photo_04.html
(this is an early Pontiac Q-jet, but the location is the same on Chevrolet versions)

As for open the flaps on the top they will open by hand they just dont open when i gun it in the garage

Don't worry about this.  You really have to be abusive to get them open at all when in neutral.  I should have also mentioned that the choke pulloff puts a slight delay on the opening air flap.  When the vacuum drops the choke pulloff slowly (over the course of 2-3 seconds) allows the air flap to open fully.  This delay can serve as a nice tuning point for the Q-jet (heavier/higher geared vehicles like slower pulloff, lighter/lower geared like faster pulloff).

The point is, even though they aren't opening in neutral, the airflaps should be opening when in normal use.  If it is tuned properly, you shouldn't feel it (the secondaries should come on smoothly without surge), but you can definitely hear it.  The engine sounds like it grows real set of lungs.  Now it is possible that the spring that preloads the airflap has been adjusted too tight, but I would caution against messing with this until you have done some research.  It is easy break the spring if you over tighten it or at least screw up the adjustment if you don't know what you're doing.

Scroll a little past midway down this page for some good info and pics: http://www.73-87.com/7387garage/drivetrain/myqjet.htm

[Buddy]

Ok got it thanks for the help. It just seemed a little funny to me that the vacuum line for the vacuum advance goes on the drivers side! you think they would keep it on the pass side beside the vacuum advance. Thanks again