Bead blasting pistons

[iScamp]

Was reading about someone wanting to buy some used forged pistons on another forum. He posted a picture of the pistons and asked some basic questions about CR, compression height, etc. First response he got was: If those pistons have been bead blasted, and they appear to be. They are trashed.

What's wrong with bead blasting pistons?

 

[RustyRatRod]

Nothing, as long as you don't blast the skirts. Once you do that, pitch um in the garbage can.

 

[iScamp]

Is there a coating on the skirt or does it make a rough surface against the cylinder bore?

 

[Scody21]

Not all are coated. And yes it messes up the machined finish on the skirt. Most pistons have skirt to wall clearance in the .0003 range