i recently bought an 86 iroc. sometimes when i start it up it smokes for a few seconds but then it runs clean. what could be some causes of this and could it be serious? Plus i noticed that the coolant level seems to be low even though i filled it a couple weaks ago.

 

What color is the smoke. If its white and you are loosing coolant then it sounds like you are burning it off, check for coolant leaks around the heads.

 

if it is blue(very common on older SBC's) then you valve seals are leaking oil down the valve stems, a little involed to fix, but i just let it alone to smoke on my cars that do it, until i am in there for something else, or it gets really bad(smoke at idle when warmed up)

 

Common problem with SBC engines, VALVE SEALS. No big deal unless your oil comsumption is excessive.