Anyone know why this piston looks like this. I pulled the heads on my engine to raise the compression and after i cleaned the carbon off the pistons i found 2 pistons that look like this. You cant feel it with a finger nail just looks weird.

 

I'm guessing this might be a 400E? Otherwise that’s basically a 350 piston but they have the comp distance as the 400E and 425.

 

Correct a .060 over 400 E. Has a w31 350 piston.

 

I think you are asking about the corroded areas, not the type of piston. Pretty normal after even slight use. If you had to scrape carbon off then it is definitely normal. Especially if it has been sitting for a while.