I like to go get me a hamburger and fries,,,,,sit in my van eating it while listening to my tunes which have on a few Mp3 players that I plug into my radio,,,,,,,now when you got an Early with the engine sitting next to you, it gets hot and since there are no emission controls on it,,,,you get a lot of heat and gas fumes whenever you shut off a hot engine and I surely dont like that when I am in my van sitting there eating my hamburger,,,,,,,so I put a fan on the bellypan or hang it from the floor to blow air up towards the radiator,,,,,this cools the radiator down which cools the doghouse down and you, and pushes the fumes out,,,,, I put one of those ceiling fans twist timers on it so I can set it and forget it without worrying about leaving it on and killing the battery,,,,,,I pretty much have put one on every Early around me,,,,,,now I dont know about vapor lock, but look down inside the carburetor with the engine off after it sits for a few minutes after the engine is hot,,,,,,see if gas is laying down there when you step on the gas pedal,,,,,should be dry,,,,,,,hold the gas pedal down next time its hard to start, see if that makes a difference,,,,,,remove the gas cap and run your tests in case you got the wrong one on it,,,,,,this could be a lot of things,,,,,get us some clues , then we can fix your problems,,,,,,