Correctly sized hex key is used to adjust the secondary air valve spring tension on the Rochester Quadrajet Carburetor.
Secondary air valve tension adjustment can be made on underside of the air horn with carburetor installed on engine, all access is on external area of carb. Adjusting air valve tension looser will increase opening rate of scondaries. Tighting the air valve will slow down the opening rate and can cure bogging.
Quantity: 1 hex key