It's common on all cars with carbs. What happens is when you shut down the car, the heat from the engine soaks into the intake, and the carb. When the car is running, coolant is flowing, and the natural effect of atomizing/mixing gas and air creates a cooling effect (much like using a aerosol spray can; you notice it gets cooler as you use it). After you turn off the car, the carb will slowly get hot, and the gas in turn will boil in the bowls (much more today than in the past with all the additives in the gas now), and the pressure goes up, eventually leading to it flooding out, or overcoming the needle/seat and back flowing. This leads to a condition where the float bowls are empty at next start up, and resulting in you have to crank to fill the bowls by the mechanical pump. Where an electric pump comes in is when you turn on the ignition before you start, the electric pump fills the carbs, it solves the problem but you still may pee gas down the engine which is BAD, nice way to wash down the cylinders, the electric plump route does solve the hard starting but does not solve the initial problem, which is the carb getting hot. Even when running you will get better atomization from a cooler carb than a hot carb, so any spacer/insulator will help.


I would like to add a couple of things if I may: The problem is a lot more pronounce now days than it was back in the day these cars and trucks were produced do to the fact that most gas is got 10% ethanol mix. This make the gas much more prone to perculation do to the low boiling point of the alcohol mix. It is also a lot more pronounce with the carbrated mechanical fuel pump engines over the injected electric fuel pump engines. I would like to add to that a lot of the time after sitting a short time the engine is actually flooded and you will have better luck starting by treating it like starting flooded engine by holding the throttle wide open while cranking the engine over.
Also if this has happened to you very much better smell your oil because gas in the oil has very poor lubricating qualities.

Clean it, if it's Dirty. Oil it, if it Squeaks. But: Don't fix it, if it Works!