I put my engine together about 17 years ago and it had developed a few seal leaks so I took it out to replace seals/gaskets. When I took the heads off this is what the pistons looked like. I was a little surprised. Is this normal? I assume this is carbon buildup. It wipes off the pistons no problem. The underside of the heads has the brown/tan look I am used to looking for on spark plugs so I was caught off guard seeing the pistons like this instead of looking like the heads.
