Quadrajet float bowl leaking down

[DT1]

I recently rebuilt my Quadrajet using one of Cliff's kits and the great information from his book.  Although the truck runs very well now,  I'm having an issue with the float bowl draining down.  If I let it sit for more than two days I have to crank the engine for 5 -7 seconds after I depress the pedal to engage the choke and give a burst from the accelerator pump.  When it finally starts, I get black rich smoke from the exhaust and have to feather the gas to clean it up.  If it only sits for a day, all I have to do is hit the gas and touch the key and It will immediately come to life.  I have already installed Cliff's fuel well plugs with Marine Tex epoxy but it didn't solve the issue.  The only thing I can think of is the float valve might be not sealing properly.  Any suggestions will be greatly appreciated.

[Ethan1]

I recently rebuilt my Quadrajet using one of Cliff's kits and the great information from his book.  Although the truck runs very well now,  I'm having an issue with the float bowl draining down.  If I let it sit for more than two days I have to crank the engine for 5 -7 seconds after I depress the pedal to engage the choke and give a burst from the accelerator pump.  When it finally starts, I get black rich smoke from the exhaust and have to feather the gas to clean it up.  If it only sits for a day, all I have to do is hit the gas and touch the key and It will immediately come to life.  I have already installed Cliff's fuel well plugs with Marine Tex epoxy but it didn't solve the issue.  The only thing I can think of is the float valve might be not sealing properly.  Any suggestions will be greatly appreciated.

 Are you sure the gas is not evaporating? Today's gas will do that. You hear this a lot with Qjet's and they think the well plugs are leaking fuel. Which most of the times, is not the case.

[DT1]

I was thinking that might be the problem.  I have read that the oxygenated fuel will evaporate faster.
I'm not sure how credible the source was but it almost makes sense to me because I own two
carbureted cars and they both display the same symptoms.

[Cliff Ruggles]

The only way the fuel leaves the bowl is leaking past the bottom plugs, evaporation, or draining back after shut-down.  The drain back issue can be solved by removing the clip from the needle, but they only drain back to that level anyhow.

This new fuel evaporates pretty quickly, but still should be around after 2 days.  My own carb takes about a week to evaporate the bowl dry.

There should be no rich running symptoms on cold starts if the fuel is evaporating from the bowl.  It would have to be draining into the intake to do this, or the choke isn't set up quite right.....Cliff