Good point, Truck, Here are images of two pistons I am working on. They verify what you have said about the intake side being clear. The carbon does not sand and can not be scraped off. The cooking process cleaned them. The others I have are much worse. I decided to do them all at once but one at a time. The others were much worse. Actually the hardest part was working with those "C" shaped clip rings. Thanks for your input. Dan.