I just put in a late 70s 350 from a GMC truck, and the Carter mechanical carb went in with it. My computer controlled qjet was acting up with my old 305, so i didnt want to put it back on. Now, the car is running really rich, as in leaving black streaks on the pavement where its parked. The idle screws are about 1 turn from all the way in. I was wondering where the main mixture screws are on this carb, and how do i adjust them. sorry if this is a stupid question, but i havent been able to find any info b/c I dont know the model number.
Thanks.

 

You mean where are the mixture screws on the Carter? They're staring you right in the face when you yank the air cleaner off. 2 screws, one per primary throttle bore, pointing up from the base of the carb at a 45* angle on the front of the carb. Those are the idle mixture screws. Anything above idle speeds they don't do anything, though. Above idle speed the a/f calibration is handled by the primary jets and primary metering rods.

On the QJet the idle misture screws are concealed behind factory tamper-proof caps. There's a reason for that- the computer in the car adjustes the carb's a/f mixture on the fly via a mixture control solenoid (big blue two wire plug on the top of the carb). BTW, if you run a computer controlled carb without the computer connected (or functioning properly) the carb defaults to full-rich and the engine will run like crap.

 

Oh yeah- adjusting them. Turning them in clockwise leans the mixture, CCW richens it. Make sure you keep them a fairly even number of turns out. Don't set one at 3 turns out the other at 1.