440 duster smokes sometimes???

Got a pcv and or breather cap? Are they functioning. What color was smoke? Blue,white, brownish? Could very well be rings or valve seals. Oil on top of valve cover sounds like breather pressure. That's why I asked about pcv and breather cap. Stock valve covers? Could be carbon burning off once you opened it up and let it breath if smoke was coming out of exhaust and it will appear yellowish brown and has a smell that I can't describe but different than oil or gas. Just trying to pull some more info.