I just rebuilt the AVS on my 68 383 - after adjusting timing a bit it seems to work really well with one exception - the idle mixture screw seems to have no effect; even fully seated the engine idles fine.

This is a 68 carb so there is only a single screw; I'm not a fan of these carbs to begin with as they've always been troublesome for me as opposed to Holley's.

Any idea what the cause of the issue is? floats were set per the included instructions, although I may take the top off and check again.