BC

There may be a great response in power if you were remove the pistons and make sure the ring lands are clean of soot and carbon. I found ALOT on my 75k engine. Too much for comfort.

bwoyat

Ryan,

If not a screwdriver, what's the best way to clean up the top of the pistons? Can you use some sort of cleaner or a buffer on a Dremel?

Looking for ideas?

BC

Scotchbrite? But you have to be careful with what falls into where the rings are.

Lizard928

as long as you arent gouging the piston top with the screwdriver it is safe. This stuff came off very easy
I have had some where you have to cut it off with a razor.

FlyingDog

Turn the pistons up the the top, hose them down with a chemical to cut the carbon (Seafoam, Kroil, BG) wedge something (thread, tape, putty, play doh) around the pistons, and use some plastic abrasive to remove the carbon. Scotchbrite is probably okay, but I don't know for sure.

Barry Johnson

Well, you could do what I did and throw your aluminum parts in a cold tank (washer at a machine shop [aluminum in a hot tank is very bad, btw]) and the rest in a hot tank. Your block could use a clean-up anyway! Had my whole short block assembly done for $100, and the guy left it in for quite a while.
You'd be amazed how good the crank looks after being in a tank... Got 3 comments at the shop, just in the time I was picking it up!

Are you going to re-ring? I'm kind of in the same spot you are with my build... But I found I need to get 1 piston replaced.

Pretty cool to see the detailed pics of progress. Neat!

Barry Johnson

Yeah, and PS, putting the pistons in a tank won't necessarily guarantee that all the carbon will come off... Matt's suggestions with the chemicals would work.

bwoyat

I power washed the block the other day and it came up pretty clean. I'm not sure I want to pull the pistons out right now. But you never know!

I'll try the chemical method for cleaning the tops. I already put some white lithium grease around the edge of the piston to keep any water out while I was power washing. Worked pretty good.

Barry Johnson

Whats your plan for the boost prep? New rings? Checking bearings? Cam profile or head work?

bwoyat

Like I said, I did a compression and leakdown test with pretty solid numbers so I don't think I need new rings. I'm also planning on new conrod bearings

I'm taking the heads to a shop to get the valves reseated and new valve stem seals but otherwise that's about it. And of course new head gaskets.

Barry Johnson

Ah, gotcha... Heard good things about the Cometic gasket on boosted 928s, might wanna look into that.
Dave Lomas out in Utah has them on a 600hp 928, last I heard.

bwoyat

They sound great but I believe you have retorque the heads after 3 heat cycles and make sure your heads are perfect? Which means off comes the valve covers and gaskets after its back in the car? Not sure if I'm that motivated. I think the OEM gaskets should be fine for my purposes.

Barry Johnson

I dont know what kind of boost you plan on running, but you're probably right. Personally, if you're running 8lbs or less, stock would work for you. 928s don't really blow a lot of head gaskets...

Tampa 928s

On my son's car the pistons were caked with carbon. I soaked the top of the pistons in Marvel Mystery oil filling them up overnight. The next day carbon was cleaned up with a paper towel, it really works great.

RyanPerrella

To re-torque the heads you have to pull the cams out as well. That would eliminate this for most any rational person if you ask me.

I suggested against the screwdriver because of the risk of gouging the piston which since the pistons are out, is not a risk worth taking.

When i cleaned my piston tops i used a wire wheel on a die grinder to get the heavy stuff off.

Later i bought a can of the berrymans chem-tool that Bill Ball suggeted and put the pistons with rods still attached in the bucket ad let them sit over night or two and when removed and rinsed off with water they looked great. This was the easiest way to clean ring lands as well. No scrubbing or buffing or anything they just dissolved.

When you clean everything, if you use water to rinse, just bathe everything in WD-40 this will penetrate the metal or aluminum so that no water will be on the surface and you wont have any issues with oxidation at all. The rods will oxidize very quickly if you dont soak them in some oil, or coat them in WD-40