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OK, I've never done this but how can I set the idle lower and/or set the choke correctly. The car starts and runs good but idles too high.

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To lower the idle speed, just turn out (loosen) the idle speed adjustment screw which should be on the primary (forward) throttle plate shaft end. I don't recall for a fact but I seem to remember it's on the inboard side of the carburetor, a hex-sided screw pointing forward and downward. It's pictured in the fuel section of the 55/56 shop manual in the section on the WCFB carburetor.

A quick check of the choke is that with the engine fully warm and idling, the choke valve should be fully vertical with just a bit of tension holding it in that position. But it looks like you've got a professionally rebuilt carburetor so you could start by just verifying that the index marks match the specifications, usually stated as something like "2 notches lean" or similar. If not, just loosen the screws holding the round black cover and rotate to adjust.

As O_D says, the idle speed adjustment screw is on the inboard side of the carburetor. It is not real easy to get to with the exhaust manifold so close. Once you get the idle speed set, then go to the mixture adjustment screws (the brass ones on the bottom front end of the carburetor). A good place to start is to have them adjusted one and one-half turns out. After the speed adjustment has been made, I screw the mixture screws in until the engine starts to stumble, then back out one-half turn. You may have to go back and forth on the mixture and speed adjustments to get the final smooth running idle. Not difficult, just takes a little time. Of course, the distributor points and timing need to be at their specified settings.

(o{}o)

I'm a dummy but can you be more specific when you say "inboard side of carb"? I'm going to try and adjust this afternoon.

Side closest to the engine.

Look at the lower left-hand corner of this illustration from the shop manual - just forward of the letter "B" - see the hexagonal shaped screw pointing forward and down? That's the idle speed adjustment.

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great pic, thank you! I assume to turn it out it's Lefty=loosy, righty=tighty?

Yes, it's a standard right-hand thread. And you may find it easier to turn it with a small open end wrench than a screwdriver due it's position - that's why it's hex shaped.

Can I go ahead and give it a little turn before starting the engine and it gets hot?

Sure.