FAQ17-What's that blue-black smoke when I cold start my 1975-1987 'Wing?

Oil or, if white smoke also appears, its from coolant,. Typically really dark smoke signifies that just the valve seals alone need replacing. Valve seals are a cheap fix that will definitely prevent premature sparkplug failure and improve combustion, otherwise, you will have oil slipping past the valve stem seals that have atrophied and shrunk with heat and age. Lighter smoke usually indicates further problems as stated in FAQ16.