I agree with Tiny, that a strong fuel pump is the first step in eliminating vapor lock. However, I think the Evil Vaporlock has become something of a scapegoat for all manner of other problems.
I'd follow your hunch and install a spacer under the carb, check the fuel line routing and maybe insulate the line where practical. But, I'd also consider checking/rebuilding/replacing the fuel pump, checking/rebuilding the carb, and then thinking about whether the engine is cooling itself properly, ie: the heat riser, proper coolant/water ratio, good flow through the radiator, etc.
Heck, while you're at it, just rebuild the whole engine!!!
I've been told by Carb King that the Gold Standard for addressing the crappy gas we get nowadays, is to intall a three-line fuel filter prior to the carb. One line in from the pump, one line out to the carb, and one smaller line returning to the gas tank. This allows excess gas (and vapor?) to return to the tank. With a good fuel pump, you always have good fuel pressure, and circulating, COOL fuel in the lines. A side benefit is that you gain a small percentage of horse power from the cooler fuel input. Or so I'm told.
Kinda a pain in the A$$ to plumb a line back into the tank, though . . .
Anyway, those are the thoughts of THIS shade-tree mechanic . . .
-Michael
