eb02z06

iTrader: (18)

I got these pistons from a forum member here. I was told they had some scuff marks on the skirts but it was nothing to worry to about. The pistons look brand new and were apparantly just in the car for a short period when the owner decided to go bigger so the parts that could be sold where sold. The motor was put togehter by a well respected sponser-I have contacted the seller but I have yet to hear back from them. Here are the pics of the skirts-I'll post some more tonight-they look worse in person.The marks are only on 1 side of the skirt. I was told not to use by my engine builder-he said the motor would be noisy until it got warm-what are your thoughts?

Adrenaline_Z

Those scuff marks are perpendicular to the pin which means the piston skirt
expanded and wasn't clearanced properly to the cylinder bore, or poor oil/
cooling system control was the original cause in the last motor.

That could be the major thrust side; check the orientation for forward facing
marks and if the pistons are numbered you can figure it out pretty quick.

From what I see, the piston should be fine. I would check the top ring lands
and make sure they're not scuffed. Have the pistons fluxed to rule out hair
line cracks.

I wouldn't say they're totally garbage yet. There might be some surface
finshing required to protect the metal and heat transfer characteristics.

The biggest concern would be warping of the piston from excessive heat.
In that case, they're probably not worth the risk of trying.

socalstreetracer

iTrader: (4)

good luck, I am just curious of one question, why is the torque so low 606/488? seems kinda weird for a charged car.

eb02z06

iTrader: (18)

The damage is only on the skirt and not on any of the ringlands. It doesn't feel that rought to the touch but i'm not expert. I wish i could tell you why the torque is so low-my timing is very conservative, my compression is lower than stock and i'm running the factory cats-I think the factory cats are the main reason.

eb02z06

iTrader: (18)

Here is another pic.

machinistone

You need to mic the pistons to make sure the skirts are not collapsed. Those look like crap, something was not right, clearances or dirty assembly. I can pull short skirt pistons out of our road race 350's and dirt modified 400's that have 2 full seasons on them with little or no scuffing.

How easily do the lines catch your fingernail?

eb02z06

iTrader: (18)

Mmmm this is no good Jason from Thunder sold these and said they are fine. I've pm'd him twice and no answer. Might have to put this in the feedback section if he doesn't reply.

1fastWS6

iTrader: (3)

Can they be polished out slightly and then maybe teflon coated?

STOCK1090

iTrader: (1)

You can clean them up and have them coated all you want but the trouble will be the ovality of the piston is probably compromised. A piston is not round. That piston was not happy. When you measure the piston for clearance they are measured 90 degrees from the pin. In this case the measurement maybe too small to what you really need and you could be a little tight.

Inspector12

iTrader: (29)

Doesn't really strike me as that bad I have seen a lot of factory pistons come out with simular marks so my only thing to tell you to be sure is have them checked by a qualified machine shop and you might try a couple to make sure the one your using isn't just trying to sell you some extra parts etc... Good luck!

eb02z06

iTrader: (18)

Every piston is like that-so do i need to take it to a machine shop to check them or is this something i can do on my own?

Formulated

iTrader: (16)

Those pistons don't look very good. It looks like some excessive loading on the thrust side, which is where you would expect it. I wonder if it could be from high loads and low temperatures (not letting the car warm up). They may be fine coming out of an engine, but I would not put them back in. Remember that they will run against the bores in your block, so you put your block at risk as well. For the price of pistons I would have bought new.

I don't think there's anything a machine shop can do for you either. The skirt form isn't anything they will be able to reproduce, and any material removal will only increase the piston to bore clearances.

Armageddon

iTrader: (41)

I'm curious as to the setup the previous owner had them in. Not knowing much about the old setup the first thing that comes to mind is a bad rod length for the stroke. Too great of a rod angularity; which like these guys said previously loaded up the thrust side and bound it against the wall. If the bore clearances were too tight it would have issues most of the way around the skirt, and if the piston was out of round it would show wear on two different spots 180 out. Which leaves me with excessive rod angularity?

Adrenaline_Z

The piston is naturally oval, it expands perpendicular to the pin. Your rod
theory might have value, but even the shortest rod combo wont do that to a piston.

That was a bad clearance job, or cooling/oil failure IMO. I don't think we'll
ever know the true cause.

SLED28

iTrader: (7)

You know my thoughts, not worth the risk. Hey Arun, I have 383 dished setup here, the pistons and rods are used (perfect condition), but a brand new eagle 4". I even have a nice LS6 block here ready to rock. We could even substitute the rods (I think you have some 6.125's) Can get that done in no time.

lucky

There're trashed.Might use them just to make the engine a runner but not for a decent rebuild.
Ciao

stevewix

second vote for trash, not in my motor!

eb02z06

iTrader: (18)

Actually it was only 2 pistons that had the marks-not all 8. Took them to a local shop and they said they checked out fine-some polishing and all is good.

SLED28

iTrader: (7)

Arun! Just make sure they have taper still, 3 or 4 thou from the top to the bottom of the skirt or it will rattle on cold startup.

STOCK1090

iTrader: (1)

Some guys build racing engines, some guys build good enough engines.