JIMO, I am still thinking the same thing as above. With moisture, the piston top would corrode, oxidize, and it would look like the piston top shown with pits all over, and most of it would just vaporize with a little bit of combustion. It looks like a few bits of AL on the valve faces. I can't see anything hitting on the head's combusiton chamber surface; looks like a normal cast surface. AM I missing something in that pix?