Ok, I finally got around to doing the first tune up on my wrangler. As I started pulling my spark plugs I was very surprised to see a white hard crust built up around #'s 1-4 and the porcelain arount the electrode on 5 and 6 was cracked in half. See the below image for the white crust. The engine runs great and has plenty of power. With a cracked head it would only effect one or two cylinders and the same for a head gasket. Anyone have any ideas?