Even if the fuel in that line was boiling and the vapor traveled back to the fuel manifold, the vapor would not be able to travel upstream through the manifold to get into the carburetors. The vapor would be forced through the return line.
It will help to cool other parts of the under-cowl fuel system i.e., gascolator, fuel pump, fuel manifold and carburetor bowls. The fuel in the carburetor bowls is in danger of vaporizing because it is exposed to atmospheric pressure, no longer being pressurized by the fuel pumps. In addition, the carburetors are located right above the hot exhaust pipes.
A heat shield around the gascolator will protect it from muffler heat.
Untried idea: Small scat tubes could run along the firewall shelf and be aimed at the aft side of the carb bowls. Two cushion clamps could hold each scat tube to the engine mount.
Joe Gores
