# Quadra jet air door adjustment



## Roqetman (Aug 31, 2015)

I’m looking for some expert Q-jet advice on adjustments to the secondary air doors. I’ve just recently noticed that the air doors do not completely close. 

The little spring where by the Allen head set screw is not engaged. See pic for detail, this pic was taken with a mirror with the carb on the car. It’s a hard to see but the little hook on the end of the spring is not engaged with the little shaft. I believe the spring puts tension on the air doors to keep them closed until called upon. My thought is this, connect the spring and adjust the Allen screw for the right tension on the air doors. 

Is the flat head screw on the top of the carb part of the air door adjustment? Please let me know if there are any other adjustments affecting the air doors. Thanks!


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## PontiacJim (Dec 29, 2012)

Roqetman said:


> I’m looking for some expert Q-jet advice on adjustments to the secondary air doors. I’ve just recently noticed that the air doors do not completely close.
> 
> The little spring where by the Allen head set screw is not engaged. See pic for detail, this pic was taken with a mirror with the carb on the car. It’s a hard to see but the little hook on the end of the spring is not engaged with the little shaft. I believe the spring puts tension on the air doors to keep them closed until called upon. My thought is this, connect the spring and adjust the Allen screw for the right tension on the air doors.
> 
> Is the flat head screw on the top of the carb part of the air door adjustment? Please let me know if there are any other adjustments affecting the air doors. Thanks!



Screw on top holds the top half of the carb to the main body - not an adjuster screw.

You will see the allen screw under the bottom, seen in your photo. I acts as a set screw. You loosen it with an allen wrench. You will also see a small screw/slot that is on the side where the allen screw is. This is your tension adjustment for the spring that puts the tension on the secondary air valve.

To adjust:

1.) Insert your allen wrench from underneath and get it ready to loosen the allen screw, but not just yet.

2.) Then get a small flat blade screw driver into the screw. Put a little tension on it like you were going to turn it.

3.) With a little turning tension on your screw driver, turn the allen wrench just enough so that the screw/screw driver will move for you. This lets you know that the allen screw has been backed off just enough to release its hold on the screw. No need to crank the allen screw out needlessly or have it drop out and get lost down the valley pan.

4.) Simply turn the small screw clockwise. Now if the screw does not turn fairly easy with just a little drag on it, don't muscle it, just tweak the allen wrench a hair more to release some of the pressure on the screw.

5.) As you turn the small screw, it will wind up that small spring that puts tension on the air flap. As you turn it, it will begin to apply tension on the air flap and you will see the air flap respond and close down. That tells you you have got it right.

6.) So how much tension? Cliff Ruggles says 1/2 to 3/4 of a turn once the flap goes down and is seated.

7.) Once you have the screw adjusted to apply tension on the air flap, snug the allen screw down to lock the flat screw in place. DO NOT over tighten the allen screw or you may strip it out of the casting - so use good judgement, but not too loose that the screw will slip and you lose your spring tension.

8.) My method in adjusting the air flap has always been to do it by feel. I push down on the air flap against the spring tension and observe how quick it closes shut. Too loose and the flap will be lazy when it snaps back. Too tight and it'll snap right down fast. So I go with something in between to start, and then road test to dial it in. So you can use either the 1/2 to 3/4 turn or adjust by feel. This is just your initial setting.

9.) Road test. Very easy to adjust out on the road, so bring your allen wrench and screw driver. All you need to do is head down the road and nail the gas to pop open the secondaries. If the air flap tension is too loose, you will definitely feel the engine bog/nose down and then it'll pick up and take off. If too tight, you will crack open the secondaries and you won't feel the power of the engine kick in simultaneously, it'll feel like it had a delay on the air flap and then all of a sudden it will kick in and the car will take off. I usually go for the "bog" side of setting the air flap up, and then turn the screw 1/4 of a turn to tighten the spring tension and then test again - and repeat if needed until I get the reaction from the secondary air flap that I want. If too tight at first, just reverse the procedure and loosen a 1/4 turn off and test until you like it. If you do not find a "perfect setting," it is better to have a tad bit tight on the flap than loose and experience that "bog" from the engine.

So, pretty simple. Now if by chance your spring is broke, you can purchase a replacement.

:thumbsup:


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