I should be a real small flathead either gray and right next to the carb but on screwing into the case of the motor and not the carb or it would be a small black screw with a spring under it in the same spot as I just said. You should only have 3 adjustment screws, the one you just adjusted to get the car running, one on actual slide of the carb that move in and out when you give it gas and the one where I just said.