You're having typical "hot soak" starting problems. The fuel in the float bowl is expanding and spilling over into the intake manifold, creating a flooded condition after 5-15 minutes of being stopped with the engine hot. Is there an insulator block between the intake manifold and the carburetor? If not, install one. Lowering the float level slightly might also help, but that can create a lean surge during normal driving.
A work-around would be to crank the engine with the throttle held wide open after a hot stop, which will help clear the flood quickly. Just back off to a fast idle soon after the engine starts to avoid over-revving it. It's going to run rough for a few seconds, so don't go back to idle immediately.
These situations used to be commonplace and drivers knew how to deal with them instinctively before computer dumbed down everybody's driving skills. Now if an engine doesn't start in 5 seconds or less, hot of cold, most people panic.
Jerry
