I've worked on Holley's for years. They're pretty much fool proof so long as they are clean, and not that they are sensitive to dirt because some people have left them on their engines for years and hardly never rebuilt them. A Q-jet must stay clean because it's so sensitive to vacuum. Holleys are so simple there's not much of anything that's vacuum operated to have to adjust, like nothing. That's why Holley's work so well is because of their simplicity. There's no moving parts internally, unless you want to count one little rubber diaphragm at the accelerator pump. Holley's work off of vacuum and air. That's why they work out of the box with no or very little adjustment because they are set at the factory and that's it! People talk about they've got this Q-jet they've tweeked and tuned and did this and did that and now it runs perfect. Really? I've rebuilt mine I don't know how many times sitting on the curb in front of my truck in the street, with a little wash tub, a spray can of carb cleaner, a couple of red rags, and a can of computer dust air. Throw a kit in it and put it back on and have to do nothing else to it. Right there in the dang street! I'd like to see you do that with a Q-jet.
My idea on your carb is dirt in the bowl area, or a leaking gasket between the bowl and the body. Maybe you accidentally tore it or something. Maybe got a bit of dirt in it and it keeps getting sucked in a orifice, then it falls out and it works again, back and forth.
Don't give up on getting it going until you find out what's wrong with it. Replace the needle valve and seat. I had one in my carb one time that had been in it for a long time and the carb just didn't seem like it wanted to go and I kept having to adjust the needle and seat. Then I replaced it and I never had another problem with it. You can't even see the little wear on that rubber seat and it'd be leaking a tiny bit but enough. You were doing right by adjusting it until fuel just starts coming out at the bottom of the threads, then lock it down. After that you shouldn't have to do anything to it. So long as the gaskets are good, it's clean, and whatever needs to be replaced, a tiny handful of parts like one or two and that's all. Q-jets on the other hand...omg!
