Vapor lock: I suspect (but don't know) this car has a return fuel line back to the gas tank, so cool gas is moving all the time by the T to the carb.
WAI: The car will run rich, unless the carb can reduce the F/A ratio enough to compensate. The economy might still be better. Look at the color of your spark plugs to figure out how well it is doing.
look at normal, overheated, and carbon fouled in these pics
http://www.verrill.com/moto/sellingg...colorchart.htm