Virg,
You could have a couple of different problems. Does it turn over and not start or does it not turn over when it is hot? I agree with the above about the starter but if it turns over fine but fails to start you may have a fuel problem. Some carburetors like Edelbrock tend to flood over when hot. When it finally starts does it run OK or does it run rough for a few seconds? If it runs rough it is an indication of flooding.
Fred