Quadrajet float bowl leaking down

[DT1]

I have always had a problem with my Quadrajet leaking down after sitting for more than two days. After I depress the gas pedal to set the choke, I have to crank the starter for at least 5-7 seconds to allow the float bowl to fill. When it finally starts, I get a big puff of rich black smoke for a second.
I sealed the bottom well plugs with Cliff Ruggle's kit but it didn't solve the issue.
Does anyone have any other suggestions to fix the problem. The only thing I can think of is that the float valve isn't seating properly. Maybe the power piston spring is too light?
Any suggestions would be appreciated.