Are these Wiseco Pistons?
 

I pulled one of my motors apart and I just want to know for sure what kind of pistons these are. Also, what can I use to remove the carbon from the piston surface? I tried a little bit of Seafoam on a rag, but it's being very stubborn and before I go too crazy I thought I should ask. This thing was completely covered and the dish was almost filled in with carbon before I started cleaning it.

steam is a powerful cleaner....don't look stock, about as much as i can help you.

Are you going to remove the pistons for cleaning? Or are you just wanting to clean the tops while they're in the block?

I'd take them out and use a wire wheel on a drill to clean the tops. use something less abrasive on the skirts, then wash and oil them. There's a million chemicals in the world. Wire wheel beats them all.

'cept steam or nitrous. :)

Oh, and I got the knock sensor today man. Thanks a million!

I really don't want to remove them. I'm just an amateur when it comes to this kind of stuff. I mainly just want the peace of mind knowing that when I throw 25# at this motor, the bottom end will be able to handle it. And this will validate what the seller told me was inside of it.

No problem, glad I could help.

Seconding the wire wheel idea. A soft-ish or loose weave will take off the deposits without damaging the metal. After you get most of it you can seafoam the little bits out. Put some oil in when you do it to keep from scoring or catching. Blow it out with air afterwards and you're done.

They're definitely not stock manual. To me they look like automatic pistons, the extra volume looks about enough to drop compression to 8.8.

Take advice from me, if you do it still in the block, USE A VACUUM!!! I did mine in the block the first time around and just figured the carbon flakes and gunk would find its way out (since they were at TDC when I wheeled them), but apparently it found its way around the rings and all 4 of my oil control rings ended up gunked up and stuck, which lead to me going through 3-4 months of troublshooting trying to figure out why my car smokes and ran poorly after freshening up the head. I blamed it on head gasket/block deck or head surface, it ended up being the rings. If the engine is out of the car, why not take them out and do at least rings. Not THAT much work.

allow some ATF or carb cleaner to soak on them overnight, might be best to drop 2 pistons at a time into the wells/cylinders to get more fluid in there.

and don't forget to change the oil once assembled, but I'm sure you probably thought of that already.

just bolt the motor back together and run a little (very little) water through the motor. It will make everything squeaky clean. I wish I had the before and after pictures of my vw from this.

that's what I'm sayin'....

a little steam cleaning goes a long way:

http://boostedmiata.com/blown_engine..._piston004.JPG

that's what my motor looked like when I pulled it at 90K. All it took was a vacuum line and a little water. I suggest searching "bucket water" as a keyword and magnamx5 as the user name before doing such cleaning.

Those look like Wisecos. I have pics of my motor build on my camera at home, and I'll get them up tonight.

Is the intake valve relief bigger than the exhaust?

nevermind, dumb question.

You can use some moly greese on the walls of the cylinders. It will catch the chips and prevent it from falling down to the rings. When you're done turn the motor by hand through a rotation and the contamanants and greese should be at the top of the bores for easy wipe off.

Make sure you tape over the oil and water passages though.