340 has a hard time starting when hot?

So driving my fathers 340 dart, every time I take it for a drive and park it, I cannot start it? Usually I take it to the local car show, car runs abit hot, but after sitting for 1-2 hours its really hard to start? Any suggestions....

THanks
I use a thermal block gasket between the carb and intake manifold on my 340 with a Edelbrock mechanical fuel pump, steel uncovered fuel line - no issues even in the hottest of weather.