When you say idle set screw, are you talking about the idle "stop" screw?

Look closely at the throttle control horn. Is there a small recessed screw inside it? Or is it just a screw holding the control horn on? he low end needle screw is often (usually) inside that.

Otherwise, on an air bleed carb, the air bleed set screw is located on the side of the carb, and there's a tiny hole in the front of the carb body.
Dennis-