Some carb advice for a new guy.

['68OrangeSunshine]

Originally Posted by Steeveedee

Not sure what you mean by 3-stage metering rods. I bought an AVS2 and a calibration kit (slight surging at part throttle). The rods in the kit are small at the tip, taper, and further up have a step. I suspect that that largest diameter doesn't actually enter the jet, given the carburetor configuration? I haven't changed anything yet, as it's a real mother female dog to get up there when I'm using a cane. At least I got the carb on and the truck running.

Way back when Carter still built carburetors they built the AFB -- Aluminum Four Barrel and the AVS -- Adjustable Vacuum Secondary.
When they quit the carb business [in the Mid '80s -- due to factory fuel injection] Federal Mogul took over building AFBs for the aftermarket. Edelbrock also got some AFBs from the same Weber factory still making them, and marketed them with a higher polish and emphasis on high performance parts.
To my knowledge, no one still built the AVS. [Until Edelbrock revived it fairly recently.] The original AVS carbs had three stage Metering Rods and Jets. The middle apertures were to dial in midrange performance. I have an old Carter AVS i found discarded as a prop after a movie wrapped. Instead of annular rings in the secondaries, it has 1/4'' x 2''[~] probes with many small holes. I bought Edelbrock AVS2 Rods and Jets in the hope of rebuilding it, but found they were only two-step. Edelbrock consolidated logistics by converting the AVS2 to use 2-step parts like their Performer [AFB]
Federal Mogul quit making AFBs in the early 2000s.
Guys at the local Hot Rod Shop said my rebuilt AVS would ''Probably run like ass anyway'' so I dropped the project.