Take the bowl off again. Turn it upside down. Loosen the float adjuster nut. Turn the float adjusted screw until the flat part of the float is parallel with the bottom surface of the bowl. Then reinstall the bowl and give it a try. Can't remember if you mentioned this but there should be an inlet screen where your fuel line attaches to the bowl. Make sure its clean.
Then if you get it running you can do the bowl adjustment from the outside. The engine must be hot to do this.
I pulled the bowl off. It seemed like the bowl was stuck in the low posistion (on the "top" as I held the bowl inverted, but would be stuck in the low position/bottom of the bowl when the bowl was installed on the carb). With very light pressure the bowl became "unstuck" and seemed to move freely after that. Would this cause the issue of fuel continually pumping through and forcing it's way out of the top vent?
Although hard to see in the picture, the adjustment needle was set such that the float was slightly above parallel with the bottom lip of the inverted bowl assembly:
While I had everything apart I pulled the jets out and sprayed them with carb cleaner and compressed air. No issues to report there; everything was clean. While I have it apart to this stage, is there anything else I should clean/do?
Of note, the inside of the bowl had some kind of coating that was bubbled, cracked, and peeling inside of it:
What the hell is that stuff? In my mind that's just begging for crap to get inside the combustion chamber.
I also have the float bowl off my 4412-3 carb (a Holley model 2300 500 CFM variant) sitting on the bench. From what I'm reading, this is the correct initial setting, right? It appears to be identically sized. Perhaps more importantly it doesn't have whatever weird liner sprayed inside it. Will this float bowl work on the 7448 carb without causing any issues?