My 88 Iroc puffs smoke when I start it up, but its not blue, its white. Its also hard starting (unless it sits for a few days or more, then it starts right up). I'm wondering if it could have a leaky fuel injector? B/c if it leaks, it would be hard starting a few hours later with excess fuel in 1 or more cylinders. But after a week, it dries up and the engine starts up? Any ideas? Would leaky valve seals cause white smoke, or only blue?

 

I think it is likely your rings causing the smoke at startup.

 

it's moistuir in your gas,or your heagasket leaks when it sit's over night.
350 or the big bad 305.
it's a third gen be patent with it there old 80's car's.
they requir higher maintaince, and more tlc.
i'd run some 20w-50 oil ,and keep an eye on your oil level and coolant level.
closly monitor temp and oil psi.
it's prolly nothing.

 

That definitely sounds like a dirty injector that's not closing all the way. If it was rings it'd be oil smoke (bluish) and the same with valve seals. A minor head gasket leak is a possibility, but injector issues are more likely. Run a bottle or 2 of injector cleaner through it and see if it helps. You might also want to get ahold of a fuel pressure gauge and see if it's leaking down quickly when you shut the car off (pressure should stay up for 20-30 min or more) because that would indicate an injector leak.