I rebuilt the motor on my 1982 22r, compression was good everything seemed correct. It ran well for about an hour and then began to sputter and put out an amount of black smut. It did this before the rebuild. WTF? I'm at a lost

 

Before you rebuilt it did it have a blown head gasket ? It very well could be your blowing the crap out of your cat. Look at the plugs. That will tell ya if its the engine.