When i first got my car, it was running incredibly rich, black sut was coming out of my muffler. It was just horrible. I adjusted it and then it ran fine(didnt have black stuff), well my dad which knows nuttin about 4 cylinder carbs tried adjusting it more. Then it runs worse. SO he tries again which done succeed.He tried adjusting it again(the black knob) and now it runs the same, but the black stuff is back, any help???
