Doing initial tune on freshly rebuilt 67 302. Everything bone stock & blueprinted, including the points ignition system and 3911 780cfm carb (4150 series) rebuilt by MacNeish.
I was having trouble setting the idle and discovered I'd installed the choke rod upside down and besides not operating properly it was binding with the fast idle cam. Fixed that, adjusted it "just right", checked the fuel bowl levels (fuel at bottom of thread), and tried starting up again.
Now, when I crank for a little bit and stop, fuel starts bubbling out of the main vent tube. If I crank for say 20-30 seconds, fuel is literally POURING out of the vent tube.
After cleaning off the intake and I open the sight plug on the main fuel bowl, fuel does in fact come out until the level is back below the threads.
What the heck did I do now?!?!?! Except for the choke/idle problem, everything was hunky-dory.