They didn't have this type of fuel back then either.
Bingo!! Just like our oil they changed the blends for modern cars where fuel is delivered to injectors under higher pressures not being stored on top of a hot motor. Like mentioned, check if there's fuel in the carb after getting it nice an warm after it's sat. Another thing to try is run the gas out and fill it up with non ethanol fuel if you can find someone that sells it and see if it quits.
This is where the sight glass is very handy, easily visible.
the problem clearly sounds like vapor lock. it does happen extremely quickly, try to touch anything in the engine compartment after a drive and see how long you can leave your hand there. gasoline doesnt really boils, it more so instantaneously vaporizes (which is why its so volatile and useful for internal combustion engines) and that occurs at only 93F (fill up your lawn mower from a plastic jug in the summer and that jug is puffed out and swollen from the vapor having expanded) everything under the hood is way above that. bringing back my heat transfer class, follow that curve up to a couple hundred degrees and the flash over speed is exponential. thats why frozen turkeys blow up in turkey fryers, the ice skips liquid going straight to gas, and those millions of bubbles escaping the oil it what violently sprays the oil everywhere. those tiny bubbles of gas vapor within the liquid violently expand fill the space, pushing the liquid gas out of the way, causing pressure on both sides of the bubble and lock it up. what stops it from occurring while running is the steady movement of the gas with cool gas coming in right behind it, as well as that fact that youre dirivng, air is moving through the engine compartment. it doesnt have to happen in the carb either, it could easily be a spot in the fuel line thats near something warm. that spot in the line has only a bubble of vapor and causes vapor lock. the mechanical fuel pump cant push gas if it cant pull it either. so yes one solution is an electric fuel pump that has the balls to push the gas through the bubble. you could also run your fuel lines as far away from the motor as you can. an extra inch or two from the pump to the carb lifts the line farther from the motor and will help alot. or another solution is to look at your intake manifold and see if it has a crossover. im not familiar with that late a model of motor but its right in the middle of all the oil smog BS. if the intake is stock it might have a "heater" built directly into it, and that will vaporize gas in the lines or the carb. either its an exhaust or more likely a coolant crossover. the intent was to heat up the intake to help carbed motors start easier in colder weather so it can start faster and be running at its intended efficiency much quicker. change your intake gasket to one that has the crossover blocked off, and it will probably solve your problem, if not it will at least help it quite a bit. This exact $15, 1 hour fix has solved your exact problem on three different vehicles for me.
