Cleaned/rebuilt the carb, no leaking float, new bowl gasket and new washer on screw at the bottom of the bowl. Fuel is always dripping from the bottom of the bowl. It looks like it comes out at the screw. I have reinstalled several time and have tightened the screw very tight. Any ideas?

Look for a small pinhole in the float bowl. Hold it up to light and see if you can see any light through the bowl.

Sounds like there is an issue with the bowl. As already suggested, check for pinhole in bowl. Careful on tightening the bowl nut, torquing it to much may lead to more problems.
Dean

Install the gasket on the carb and then install the bowl.