Does anyone know how to adjust the air/fuel mixture on a Rochester Quadrajet 7045229 Z8 1576 carburetor? I have a 1995 Eliminator 207 jet boat with a 454 Marine Power engine. There are two needle adjustments screws in front of the carburetor, but I'm not sure which it is and which one does what. I just don't want to run too lean and blow the engine. Any help would be greatly appreciated. Thanks!!!