If it was accelerator pump, you'd get stumbling/backfiring when giving it more gas.
with draining its either through the galley plugs on the bottom of the fuel bowl or syphoning back out. try using a fuel filter with a check valve?
poor choke operation. Weak fuel pump could be a contributor...just a few idears
Edelbrock carbs blow but i see em on alot of cars, but ive never had any luck with em