Richard - go right ahead, and you are quite right on the Air Valve Secondary; I have been mistyping all night (I read a 94 to mean 64 on another board). You are also quite right on the secondary boosters on the original design of the AFB in 1957; but this issue was solved early in the development of the AFB by the tertiary secondary circuits.
However, if the AVS works well for you, you would be one of a few (hey, that makes them cheaper to buy!).
You are correct that the air valve spring may be adjusted, but all of the Carter tests showed that the airvalve worked best at the factory setting. With the AFB, one could change the air valve (there are many different ones available), and the weighted airvalve had two variables (weight and angle). Granted, most tuners do not have the inventory of these that I do. Generally the small block Chevy engines like airvalves with large angles; high torque, low RPM engines like airvalves with small angles. Using both weights and angles, one has better control of both the beginning of the valve opening, and the rate of opening.
Carter did offer some aftermarket AVS carbs during the Chrysler AVS years (1968-1971), but these are so rare, I have NEVER even seen one. The AVS was basically a smog carburetor that was a stop-gap measure leading to the much improved TQ. Again, the TQ works best when the air valve is adjusted to the factory setting.
I will admit that some of the Chrysler racers have been reasonably successful with the AVS by removing the metering rods and rejetting the primary accordingly (ala Holley). This works reasonably well for WOT, but leaves much to be desired for street operation.
And some additonal information on the AVS: of the Chrysler models, the small primary version was rated 630 CFM, and the large primary 750 CFM.
And your success simply proves there is no single correct answer.
Jon.
