Hi, lately I have been having trouble with my 65 belvedere 383. When I start it cold it starts up fine and runs good, but then after drivin for 30 minutes or so and shutting the engine off, the car wont start up again, unless i let it sit for 20-40 minutes. I can hear the starter going and it isn't clicking. My battery has a full charge, I have fuel and the car isn't over heating. Any ideas what my problem is here?