vacuum break control

[Vics63]

I'm new at dealing with a Quadrajet although I have 2 different cars with them. My question is when the car is idling the ported vacuum pulls the break and prevents the secondary air flaps from opening. When I go to wide open throttle the break does not release and the secondary air flaps can not open. Does or rather should ported vacuum diminish with more throttle?

[77cruiser]

Never saw one with ported vac. to the pulloff, but either way the vac. drops at WOT.

[Vics63]

Thanks for the response. Just trying to learn something here. Where does the vacuum typically come from? Ive got 2 different cars with Quadrajets. They both have ported vacuum to the pull off. One is a 71 bone stock car. Pretty sure that's the way it came. Vacuum drops briefly at wot but not enough for the break to release the secondary flaps . Other one does not change vacuum at WOT. I meant to get a picture but....... I'll do it tomorrow. 
Or, is it possible it wont work sitting and not under a load? This is in the garage and not moving.

[Cliff Ruggles]

All Q-jets use manifold vacuum to the choke pull-off,  not ported.

Ported vacuum would not work to apply a choke pull-off as there is next to zero vacuum on a well located ported source at idle.

Both ported and manifold vacuum fall off to nearly zero at heavy and WOT.

The choke pull-off uses a link up to the secondaries to keep the flaps from "whipping" open too quickly and causing a lean conditions.  Some pull-offs being sold these days are WAY to quick for opening rate as they have little or no restriction in them.

A pull-off that opens too slow can also have a negative impact on full throttle performance when you go to full throttle.......Cliff

[Kenth]

Thanks for the response. Just trying to learn something here. Where does the vacuum typically come from? Ive got 2 different cars with Quadrajets. They both have ported vacuum to the pull off. One is a 71 bone stock car. Pretty sure that's the way it came. Vacuum drops briefly at wot but not enough for the break to release the secondary flaps . Other one does not change vacuum at WOT. I meant to get a picture but....... I'll do it tomorrow. 
Or, is it possible it wont work sitting and not under a load? This is in the garage and not moving.

Correct, the secondaries wont open unless you put some load on engine for the vacuum to drop enough so the atmospheric pressure can overcome the preload spring tension on air valves.
This wont happen in the garage not moving the car.

[Vics63]

A couple of pictures of the 2 different carburetors showing where the vacuum line to the pull off is connected. Am I correct in calling this ported vacuum?

[Kenth]

No, both your pull-offs are connected to constant manifold vacuum as they should.

[Vics63]

Thank you for the replies. I've learned something new today. I've spent all morning reading up on this and it sounds like the only ported vacuum is on the front drivers side of the carburetor? That is where the vacuum advance is connected on both of them. So the pull off releases when manifold vacuum is lost but it seems very slow when I disconnect the vacuum to watch it. I would love to see it in action but I don't know how I would accomplish that.

[Cliff Ruggles]

Get rid of the rubber hose on the pressure side of the fuel pump, very dangerous especially how fuel tends to "eat" rubber these days.

I also see general use of Teflon tape.  ALL of the connections used on the Quadrajet either have gaskets (fuel inlet housing) or inverted flare (fuel lines).  They do NOT need any additional sealant and Teflon tape can and will find it's way into the carb and cause issues........Cliff