[1QuickS]

Fuel in fuel gallery from idle jet to idle mixture screw will drain fuel into cylinder after shutdown but this is a small amount.

I assume engine runs fine on the idle/progression circuit. I also assume "Lean Best" idle adjustment can be achieved on each cylinder. If no then check to see that gasket between top cover & main body does not block air correction jets for the idle circuit; these are the little brass jets that are about 3/16" in diameter & pressed into the top body just inboard of each idle jet location.

Also, check to see that the idle air correction jets are clear; their orifice diameter is 1.10mm for IDA and 1.40mm for IDTP Webers.

The Bruce Anderson/PMO float bowls venting scheme was developed by Ferrari for their 365BB & 512BB which used Webers. The point of the drilling is to vent percolating fuel into the throttle bore before it goes up the vent pipe & down onto a hot engine. I no longer utilize this venting method since it floods the idle circuit on the way into the throttle bore. I have developed an alternate venting method. A secondary downfall of the Bruce Anderson/PMO/Ferrari venting is that during high speed/G-loading cornering the fuel in the float bowl will flood the idle circuit on one bank of carbs which results in a rich stumble upon throttle application.

Check to see that fuel tank is vented, if not then internal tank pressure can overcome float needle valves & allow fuel to flood engine.

Hope one of these rectifies the issue, if not then when it is remedied I would like to know what the fix was.