Why is my car overheating?

[alethia]

I have a 76 Lemans, I have recently changed the thermastat and water pump. It seems as though the radiator is blowing antifreeze back into the water bottle and it keeps running hot and engine has smoke coming from it when I drive it for a short distance. just want to know what other options are there to keep my car from running hot. I was told it may be a cracked head but my oil is not showing signs of mixing with water, Please help