I just got my pistons and rods the other day. I got some questions about the pistons though. I hear a lot of people talking about sanding and buffing the piston before install(or also reffered to as finishing touches). What exactly do they mean? Is it required?

 

I noticed the valve reliefs on my JE pistons are pretty sharp. I'm going to sand them down some before I put them in.

 

You want to sand the rough edges on the top side of the piston. They can cause hot spots on the piston and cause detonation. Basically, sand down all of the ruff edges on the top of the pistons, any edges on the valve reliefs.

 

just around the valve reliefs? Wat the heck am I supposed to use? Sand paper?

 

Check Larry's board under piston prepping.

I started on mine today. Used a carbide tip on my dremel and some fine wet/dry sandpaper. My friend has the Scotchbrite I'm going to use, so I'm just waiting for that to finish them off, but this has how it's gone so far.

You can see how sharp the valve reliefs are:


Still a bit ruff. but almost there:

 

Geeze... I can't believe a manufacturer would deliver a forced induction piston in that state... remember to leave a semi-rough finish...

 

i am contemplating doing this to my new weisco's. there 9.7:1 81.5mm pistons going in a GSR block. my question is this, after you file away the sharp edges do you guys weigh the pistons to make sure they all weigh the same? or will the little bit taken off not be enough to throw it off?