Windward - an interesting post. Trial (and possibly error ) can always be enlightening. In your case, it appears to have worked to your satisfaction.

Adjusting the throttle operating rod such that the ends are closer will cause the secondaries to open sooner.

Adjusting the throttle operating rod such that the ends are further away from each other will slow down the timing of the secondaries, but could also result in the secondaries not opening to the full position, drastically reducing the CFM of the carburetor (sometimes not a bad thing).

Carter built 505 different AFB carburetors when Carter was still in control. I don't count the Federal Mogul/Carter remakes or those produced by Weber USA or the e-clones in this count. I have specifications on most of the original Carter units.

One of the "calibration" pieces used by Carter was the auxillary air valve. I first noticed this when researching the SD 421 dual quad carbs about 35 years ago, and noticed that the dual quad air valves were much heavier and much flatter than other air valves which I had observed. This caused me to research further, and I found that, IN GENERAL, Carter used a smaller angle (flatter) on the airvalve on "torquer" engines to delay the initial opening rate of the airvalve. The "screamer" engines used a much more agressive angle, to whip the airvalve open sooner.

Unfortunately for those of us who bleed Pontiac Blue, Carter's aftermarket sales were primarily "bowtie"; thus the aftermarket carbs were calibrated for bowtie engines.

On a related issue; many who install an aftermarket carburetor are looking for power. This can be accomplished by supplying an A/F ratio that is in the 11~15 range. Generally, for street driving, an A/F ration this low is not necessary, and owners of these carbs often experience much worse fuel economy than is necessary (definately an issue with today's fuel prices). A carburetor which is carefully selected and calibrated for a specific application should be capable of both excellent power and/or excellent economy, depending on the desires of the driver.

Jon.