[Bruce Edwards]

Do you have a spacer between the carb and intake? The paper thin gasket is going to move to much heat to the carb.
The other thing to do is install the vent whistle. This little jewel will move the vent to the front of the bowl and makes it harder for the fuel to go out the vent.
One other thing you need to check is the full pressure. If it is to high the float will not hold it back and will cause the bowl to over fill.