There's an idle mixture screw somewhere on the side of the carburetor. I'm not familiar with Zenith carburetors so I can't tell you more than that. They're all pretty similar, though.
Have you checked the fuel pump pressure? If the pump is putting out too high pressure, it may overtop the bowl and flood the engine. That would mean it's too rich rather than too lean. Airtex is a horrible brand, by the way. I had two Airtex pumps fail on my Cadillac because the inlet and outlet valves were not staked at the factory. They popped out of their seats. I had 2 or 3 Airtex brand pumps fail on my F-100 in just a couple months of use because the diaphragm tore. Friends have had similar experiences.
Is the Pertronix still installed?
What is the status of the dizzy? Is it new? Was it rebuilt? Is it 70 years old and worn out? Check to see if the shaft wobbles at all if you try to move it by hand.
Last edited by Otto Skorzeny; 12/06/2022 7:46 PM.
