How to adjust carburetor mixture screws
Here's how to find and adjust the mixture screws on your carburetor. If you are doing an initial setting after rebuilding, turn each screw out 2-1/2 turns from lightly seated as a baseline to get the engine started. Note that metering-block style carbs such as Holley and Demon more often have one or 2 mixture screws in each metering block depending on the number of venturi. Also those may not be located at the bottom of the carb as in factory carburetors.
High speed idle cam discussion
Here's a look at where and how to adjust the high speed idle cam's adjustment.
How to adjust Quadrajet/Dualjet fast idle
Quadrajet/Dualjet Rochesters have a fast idle adjustment screw that is separate from the base idle screw.Here's how to locate it. NOTE THAT THE CHOKE ITSELF MUST BE WORKING IN ORDER FOR THE FAST IDLE TO FUNCTION.