http://home.wi.rr.com/montecarloss/airvalve.html



"The secondaries on Q-jet carbs have a secondary air valve spring that is adjustable which determines when the air door butterfly will open, allowing air to rush through the big secondary side of the carb. This has the obvious advantage of being tunable compared to some designs which aren't, such as AFB style carbs (which are great carbs for many other reasons). The problem is that changing the air valve spring setting is less than easy unless you have 3 hands and some time to kill. I found this simple tip in the November 2000 issue of Car Craft magazine that shows a way to make tuning/setting the air valve spring tension a breeze. The following text was taken directly from the magazine as printed, but I think there is a small error near the end. See my note following the text."

 

Is it similiar to this?
http://www.professional-products.com/airflo.html

 

No, the former is a lame attempt at making the AV easier to adjust. It won't be linear, and I can't imagine it operating smoothly.

The latter is an attempt to smooth the airflow path within the air cleaner to improve flow into the carb.

 

Yea, I stumbled on that a while ago and posted it up here.

Sounds neat, but I prefer to stick to the factory way of adjusting it.

 

Me and my cousin replaced the 302 in his old Ford truck with a Qjet a couple months ago (quite an adventure, lol).

Once we had it running and got to tuning the AV in the horrid Canadian cold, the AV tension spring broke. We tried this (the second one... "pic B") as a quick fix, as its his daily driver.

Beleive it or not, it actually works, and it works really well! Adjustment is a snap, and it works really smoothly. Now, I'd still fix it properly if it was me, but that method works just fine IMO, and would be a great modification for those using a Qjet on a race car. Tuning is much quicker and simpler.

 

I can't see CarCraft publishing a tech tuning tip like that if it didn't work?

They got a big rep tp uphold to be spreading false tips like that.
Sure they would toss in another advert page over publishing stuff that don't work.

 

I don't see why you need the big spring at all. Couldn't you take the vacuum break actuating rod out and use the stock AV tension spring?

I can see the issue of it not being linear, or the same as the stock AV tension setup. The stock AV spring cams over to the center of the lever radius when the valve is open all the way. That's the best way I can explain it. Take an old QJet and flip it upside down and watch the stock spring when you push the AV open. The spring tang slides down the arm to the center...camming over I guess...

I'm interested in this because I think my vacuum break is screwing me when I'm at WOT (Weiand 142). At times I think the carb is getting just enuf vacuum again to close the AV. I want to take the vacuum break out of the equation.