So if I let car sit for 24 hours or so I have to dump gas into the bowls to get it to start and run. I have a mechanical fuel pump. If I press on throttle gas does not want to come out untill after I dump fuel into carb. What causes this, and what are the remedies.

Have you tested the pump separately? What are you doing with the choke? When you operate the accelerator does it squirt a jet of gas into the carb? Whatever is wrong it sounds like a rebuild is in order.

If you can confirm that the float bowl is mostly empty after sitting, then it's probably one of two things. Either the gas is evaporating out the vent holes in the top (I doubt because thats a lot of gas, but maybe if your temps are high and its near boiling), or your float bowl is leaking. If this is the quadrajet, its very common for the plugs in the bottom to leak. You might have to pull the carb apart and epoxy them. And if that is it, you might want to check your oil because that gas has to go somewhere, and you dont want it washing out your bearings and rings if thats where it is.

No choke. Rebuild just done, may be my pump has problems drawing the fuel through. And no, the times I have to pour fuel in the bowls it does not squit a stream of fuel when I press accelerator, untill after I get I running

very interested in this thread. Mine is '82, 305 4BL, brand new mechanical FP. Believe carb is original Q-jet, rebuilt less than 5k miles ago but sat for many years after. Anything less than sitting fully overnight it fires off perfectly and immediately. Like some magic point reached at > 8 hrs. Am curious about the plugs in bottom of carb mentioned above...do you have to pull the carb to get to them? A friend has speculated a crack in carb housing, but that seems like it would drain out pretty quickly all the time.

Ya. You have to pull carb. Not whole thing if I remember correctly. Just to half. Then you just goop jb weld over top of them.