Starter problems, I think?

I have a 383 sbc stroker running 10-1 compression and when I start the engine cold it turns over OK and starts. If I try to do the same thing after the engine has ran for a while the engine starts to turn and stops and starts and then there is a loud mechanical sounding noise, it is kind of like the same noise you hear when you try to start your car and it is already running. The starter is a stock AC Delco starter with a new bendix and relay. Do you think the problem is from heat soaking the starter? Should I buy a starter with a some more power? My battery is a red top Optima, so the battery should be powerful enough. Any thoughts?

Sounds to me like you have initial timing issues for the amount of compression you're running. From what you've described it would appear that you have pre-ignition and therefore the starter can't handle it. What is your base timing at? This is withiout vacuum advance at idle.