Quadrajetparts is awesome. I forgot about those guys ever since I found out my q-jet 4mv had cracked venturi boosters and had to swap it out for a edlebrock 1406. I miss my q-jet
"Some" of the aftermarket floats arent very well made. Seems like they skimp on the solder in the brass floats. It sounds to me like you just dont have your float adjusted properly. Or your accelerator pump is misadjusted(if that's even possible on these single barrel carbs.) Another thing I'm unsure of in these carbs is if there are 2 springs for the accelerator pump stem. A tension spring and a return spring. On the 4 barrel q jets they are like this and can cause issues if you get them mixed up. They look similar enough alike for it to happen.
The metering rod and jet are not meant to be a completely sealed fit, unlike the needle and seat that are in carbs. The float is meant to control the amount of fuel in the float bowl and this is accomplished by enabling the needle to seat in the seat and shutting off fuel flow until the float registers a low fuel level which draws the needle off the seat allowing more fuel to enter the float bowl. If you dont have the float set to the correct level, you will be flooding the float bowl. A low float level may not be exerting enough pressure on the needle in the seat and a high float level allows to much fuel into the float bowl and will overflow.
How many turns out from seated do you have the idle/air screw? It should be at least 1 1/2 but may need as many as 4 complete turns out to idle correctly. A vacuum gauge is the best way to determine where the screw should be during idle.
The metering rod is always down inside the jet's orifice except when engine vacuum is low enough for the spring tension on the metering rod to overcome the vacuum of the engine, allowing the metering rod to raise up out of the jet( it doesnt raise out of the jet completly.) Effectively allowing more fuel to enter the jets orifice and onto being atomized into the intake manifold.