Flu: White smoke is from a coolant. Head gasket failure most common, followed by crack in head. Feel like a running a compression or leak down test??

Black is oil or super rich. Rich would be running really badly and you would have mentioned that already so that’s not it.

New catalytic is like the magic pill for older cars! I got a carboratoer in one of mine that runs great but it just is not as clean as fuel injected. I have a running bet with my smog guy!

If you are planning on keeping it, replace vaccuum lines and vacuum control ( CTO )valves. These are the vaccum switches that cycle depending on coolant temp.

But all of that is after having a different smog smog guy – pass or don’t pay place.

Oh, and maybe it would be good to make a couple of high speed freeway runs to burn off stuff in the pipe and really heat up the cat. Then take in for the test while cat is hot.

Doesn’t the car have to be dyno smogged? Newer cars get the plug in test.