alright I'm a new owner of a 87 Firebird with a 305 and 4bbl Quadra-jet carb, I am learning about cars now, so I'm an amature, I beleive my car is "running rich" gas mileage seems worse than it should be, and I got black soot from exhaust, literally can catch black specks on hand if you stick it by exhaust...very limited budget as I'm a college student, love the car, but need to get at least a lil better gas mileage...suggestion and help please...how do I turn down the carb to make it not so rich running.