[Fasterthanyou]

What carb is it? I'm okay with Holley's, not so great with the others (no experience). I've only rebuilt 2 carbs and tuned 1. The floats are suposed to be set so that you get fuel coming up to the "sight" plug. You actually want it set so that the level is barely dribbling out. If you've adjusted the floats and there still isn't fuel coming up then get yourself the $20 carb fuel pressure gauge that splices into the supply line. Check to make certain it isn't your pump that's the problem. Another cheap way to check the pump is to remove the supply line, get a bucket, put your finger of the end like a garden hose and crank the engine over. Does the pump have the balls to pump fuel or not?
First things first, before doing the above, check a spark plug. Is it rich or lean, that's the first step towards understanding your issue. If it's lean (which it sounds like it is) then it could be;
The next step is to check for a vacuum leak. Get a vac gauge, again, $20, and test that you've got good vacuum when the engine starts and is running. If not, check for leaks below the carb. Things like old brake boosters with broken diaphrams or any of your vac accessories can be to blame. I had a 3rd gen that had a vac leak that turned out to be his HVAC inside the cabin!