I installed a recolored and rebuilt C9AF-9510-U on my trucks 390 that I purchased from an FE forum member some time ago. From what I know the carb was never run after the work was done, and I wanted to mock it up on my truck before I swap in the 428 that is going in with the same type carburetor.
I followed the standard Holley instructions for baseline idle mixture, etc. I fired the motor twice, and
found fuel splashed on the front of the carb and intake. The third time, I watched closely while cranking, and saw a fountain of gasoline coming from the front vent tube. Before I take the front bowl apart to check the float and anything else that might be the culprit, is there something else I might want to look for?
Also, is the rubber vent/plunger on top of the bowl supposed to sit flat at idle?
It sits cocked at a bit of an angle, not seated, but this is exactly how it looks in the Holley photos of reproduction Cobra Jet “M” carbs.