tuning the fuel mixture screws someone rebuilt the carb and said it might need to be tuned a bit more...
its pretty easy to adjust the idle mixter screws that you are refering to. you need a vacuum gage and a tachometer. hook it to a manifold vacuum source. turn the idle mixture screws in till they bottom out. do not torque them down. just stop when they bottom out now back both of them out 1 turn. start motor. set idle speed to desired rpm (750 if you dont know what you want). look at the vac. gage and note its reading. now screw each idle mix. screw out 1/2 turn. if the vac reading increases then go 1/4 further out, if it goes down the go back the 1/2 turn and then go 1/4 turn in. the idea here is to keep both sides the same and to get the highest vac. reading you can. that will give you the best idle mixture. to further tune the carb you need to learn to read the spark plugs or get a wide band o2 sensor to know how the motor is running.
Just my experience, but I've never had any luck with the 2100's. The Holley 2300 is a much better performer. And easier to fine tune. As in adjusting the accellerator pump linkage and float settings. You don't have to "bend and guess" to make it work.
