howdy, i have a holley 4bl on my 351w mach1 any way the other morning i got on it rather hard and now the carb seems messed up[idle,popping noise in the exhaust,black exhaust and very rich]any ideas what i have done and how to fix..thanks
Does it idle really rough and try to die? How is the fuel pressure on the carburetor side of the fuel pump? Sometimes a sudden surge in engine RPM can shoot the fuel pressure high enough to bend the mounting tabs for the floats, opening the check valves continuously. This was a constant problem on the old 68 GT390 with a Holley 4150 4V carb, at least until the addition of a fuel pressure regulator and a new front float. Your problem sounds a lot like the one I had.