[Kenth]

The heat from the crossover is one of three factors that will make a combustible mixture of the gas.
The other two are velocity and amounts of fuel used.
Reducing the heat need compensated by the other two meaning you´ll have rev the engine higher and feed extra gas to the intake.
This means nothing to the 1/4 mile racers, they start at 4500 rpm´s and drive only a 1/4 mile a couple of times at weekends.
For a street driven vehicle this means worse drivability, economy and performance.

Fuel dribbling/percolating up to a half hour after shut off is often a result of the fuel line too close to hot engine parts rising the fuel pressure between the fuel pump check valve and carb inlet valve. This pressure can exceed 20 psi at times and there is NO inlet valve that holds against that kind of pressure.

I cured this issue on my 1966 Tripower GTO by using an electric fuel pump w/o check valve 25+ years ago, No heat insulators, no blocked off crossover, no percolating, no problems since. Also using the revised vented throttle body gasket in the end carbs makes for easier hot starts.

FWIW.