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Could somebody please tell me on the Carter 2bbl for my '54 Clipper Super L8 (WGD?) which spring loaded mixture screw on the front bottom base of the carb is the high idle and which is the low idle screw? And, with that in mind, which screw should I adjust first after the engine has warmed to operating temperature, or does it matter? Also, I'm under the impression that a starting point for adjusting these screws is all the way in and seated gently against the stop, then back out the screw 1.5 turns and go from there..does that sound right? Is there something more scientific too it?

Thanks again

Those are the idle mixture adjusting screws, one for each barrel. They are adjusted to make the mixture leaner or richer so that the car idles properly, both should end up pretty close to the same adjustment. Others here have given a good procedure for adjusting them using a vacuum gauge.

The idle speed screw is by the linkage on the carb...if you crank it in you'll notice it opens the throttle some and idles higher, and if you back it out it lets the throttle return more and idle lower.

If i recall, the "fast idle" is controlled by a cam where the idle screw touches...it makes the throttle stay open more, then rotates with the choke and when the choke opens, it lets the screw return to the warmed up idle position.