Bill,
The use of a wooden clothes pin as a "heat sink" is the remedy that is always described (and it supposedly worked). Since wood does not hold/absorb as much heat as just about any metal, do you think that the reason that this worked might have been that the clothes pin acted to move the fuel lines away from the hot engine/manifold?
I agree with you that vapor look is highly unlikely on a Stovebolt engine, especially if fuel lines are following the original routing and as long as the fuel lines are attached to the engine at the original locations (at fuel pump, at the thermostat housing, and at the carburetor or the fuel filter at the carburetor).
