Adjusting spring tension on QJet Secondary

76BBSub · September 24, 2001

I finally got around to adjusting the spring tension on my QJet secondary air valve (the rear "flap").

Here's the trick...on the right (passenger) side of the carb, open the secondary air valve by hand. There's a screw on the side that rotates when you open/close the air valve. Right below it is an allen-head socket set screw, it's about 1/8" allen wrench. Put a screwdriver in the one on the side and hold slight tension on it, then loosen the set screw just enough to allow you to rotate the screw on the side. Let off a little on the side screw and count the rotations until the spring tension is released, this is your baseline setting so that if you totally screw up you can go back to the way it originally was. Now, tension the spring about 1/2 turn or so, and don't forget to re-tighten the set screw before you remove the screwdriver from the side screw, or you'll have zero tension. Go drive the truck, if it bogs, adjust it again.

The problem on my Suburban, which I just found, is that the vacuum diaphragm is holding too much tension on the lockout mechanism...I think I will re-drill the orifice on it and see if that helps.

Torque Junkie, hope this helps, let me know if you have questions, comments, etc...

Jeff

Torque Junkie · September 25, 2001

Jeff

I'll have to look again at my carb. I've learned after a little research and playing with the demo's at NAPA, that my CarterAFB is essentially an Edelbrock Performer 600 cfm Carb with different name. So now I know a little bit more about how the linkages all work together and what-not.

The screw you mention doesn't appear to be visible from the outside,. Is it by chance inside of the carb, or is it outside? Or, I wonder, if it even exists on my model?

I've run into a major electrical problem that my dad and I are gonna have to spend a number of days working on. Check out my other post for details.

After I fix the electrical goof, then I'll put my focus back onto the carb running in tip-top shape