why does my firebird let out smoke when started

This is commonly caused by oil leaking past worn valve guides when the engine sets.

Or the valve guide seals have cracked and broken away from the guide. Valve guide seals is usually the repair for this problem however it is a bitch to do.

Also check your pvc system. Under certain circumstances you can get a clog that can cause pressure in the head and force toil through the guide into the cylinder.

usualy bad head gasket or valve seals depending on color of smoke

valve seals .