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I began tearig the engine down on my 1995 Indy 500-carb and got the cylinder head off. The crown of the pto side piston and head have what appear to be tiny marks or pits in them. You could say it has a sandblasted look to it. The mag side cylinder doesn't have this though. Both of the cylinder walls and piston skirts look to be in great shape with no appearance of overheating. The piston crowns on both pistons have darker black carbon on them evenly spread. Although, there appears to be significant blow by on both pistons well below the second ring. The motor has close to 6000 miles on it I was plannig to put new crank seals as preventive maintainence but now probably will put new pistons and rings in it and have the cylinders bored 0.010 or 0.020. My main concern is what caused the sandblasted look on the crown of the pto side piston and cylinder head. Do I have a larger problem looming? Also, any time after I ran the sled; I always checked my plugs and they were always dark brown to black in color on both cylinders. Thanks to anyone for some input
 

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At some point that piston had detonation, that's what caused the sandblasted look. (if the plugs are brown now, it is no longer doing it)

If all the pits are coated with carbon, it was a long time ago.
 

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I have a set of oversized 500 pistons for sale if you are interested. They came out of my 94 EFI 500, and are listed in the for sale section.
 
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