I'm just wrapping up swapping my GTO back to a 400 from the Chevy 350 it had when I bought it.
Spec wise, it's a '67 400 block with 11 bolt water pump, '68 intake, and '68 #16
heads, with what I believe to be an 041 cam, or at least something very similar. The current carburetor is a new Jet Performance quadrajet, #32102
, which I've made absolutely no adjustments to.
The motor starts up great, will idle fine, and runs good through the rpm range while parked - haven't been able to get it out on the road to test it under load because I can't get it to run long enough to try it. If I let it sit and idle for a bit, then cut it off, it won't crank again - it tries, but sputters and coughs for a few seconds until it dies.
Pulling the plugs shows that they're very black, so that says to me it's running rich. The other thing I noticed this weekend is that it started pushing fuel out the top of the carburetor, even after it died, around the accelerator pump. What would be the cause of this?
I feel like I can rule out the fuel pump, as I don't have the same behavior with the quadrajet from the Chevy, or a quadrajet from a Firebird Sprint that I had lying around. Would you agree? In those cases, the Chevy still runs rich, but that was true of it on the Chevy as well, and it doesn't foul the plugs like this Jet carb is doing. The Sprint quadrajet seems to not deliver enough fuel, which is probably true given that it was for a 6 cylinder.