[Martin_T]

Hi

Scratched one of my pistons (KB hypereutectic). Its a small vertical scratch across the outer surfaces of the top two oil ring grooves. Its very light and I can just feel it with with my finger nail. Should I try and polish out or jsut leave it? These are going into a Ford 302 Block with a 347 stroker kit.

Thanks

Martin

 

[arnoldtx]

Sounds ok but I'm sure you could reduce the scratch some with some lite polishing.

 

[bartlettracing]

best just to rub it out with a little fine sand paper... then reclean piston

 

[wagger66]

Agreed ... and keep polishing localized yet try to get it all out with no sharp edges and finish with 400 grit and don't do it again

 

[Martin_T]

Agreed ... and keep polishing localized yet try to get it all out with no sharp edges and finish with 400 grit and don't do it again

Cheers guys

you always think the worst when you do something like that. Nice to get a bit of reasurrance that its not the end of the world (or the engine!!).

Thanks

Martin

 

[FEandGoingBroke]

LEAVE IT LEAVE IT LEAVE IT LEAVE IT!!!!

The Scratch is a Divot, if you polish it down you're making a deeper divot.

Leave the darn thing be. ! ! ! ! ! ! ! ! ! !

IGNORE IT!!!!!!!!!!!!!!!!!!!!!

 

[n2omike]

Just knock off any ridges you can easily feel. No need for it to be perfectly smooth and invisible.

 

[bartlettracing]

DO not just leave it be.. It may be a divot,but Its a divot with high spots... you need to knock the high spots off and be sure it didnt cross the ring lands. if it did you need to be sure to debur it. Any tightness on the rings can lead to big problems.

 

[Hottarod]

Either way won't matter. Piston doesn't hit the cylinder walls anyway unless you are into a slap situation which is a notta good thing.

As long as you didn't break a ring it will be fine.

 

[PSIG]

+1 on just lightly deburring. I would use a little Swiss file to deburr just the places that are high enough to catch your fingernail, following any original machining grooves or features. You do not want to remove the scratch - only any high spots. Hardly anything, and you'd likely be fine if you did nothing, but it's good practice to be sure there are no high spots to interfere with the fit of the rings. It doesn't sound that bad.

David

 

[Marauderjack]

LEAVE IT LEAVE IT LEAVE IT LEAVE IT!!!!

The Scratch is a Divot, if you polish it down you're making a deeper divot.

Leave the darn thing be. ! ! ! ! ! ! ! ! ! !

IGNORE IT!!!!!!!!!!!!!!!!!!!!!

^^^+10^^^

If anything peen the high spots down but DO NOT file or "polish" it out!!

 

[retyler]

+14 As long as it doesn't effect the ring lands don't worry about it.

 

[DanH]

Do what PSIG said in post #10 .

 

[FEandGoingBroke]

Scratches are NOT high spots they are by physical description a LOW spot. There is 100% nothing to worry about.

 

[DanH]

Scratches are NOT high spots they are by physical description a LOW spot. There is 100% nothing to worry about.

FE , time to play in the sand box .
don't have a sand box , the cat's box will do

level the .. (depends type of box) contents , then sratch the surface .

what do you see ?

 

[retyler]

Scratches are NOT high spots they are by physical description a LOW spot. There is 100% nothing to worry about.

Wrong, wrong. anytime you dig a hole, something comes out of it.

 

[FEandGoingBroke]

Yes, and the OP did not mention anything about a LUMP of metal at the END of a scratch...

Its a small vertical scratch across the outer surfaces of the top two oil ring grooves. Its very light and I can just feel it with with my finger nail

Nothing to worry about, please go about your day.

 

[Das Jager]

Yes, and the OP did not mention anything about a LUMP of metal at the END of a scratch...

Nothing to worry about, please go about your day.

I wish I had taken pictures of the Ross Dome Pistons I reused on a 347 Stroker Motor I built for my personal race car once. I bought the motor and car from some guys that had been spraying it and (it had unbeknownst to me) at the time of purchase a cracked cylinder wall.
The bottom half of every piston looked like they had been 500,000 miles. There were no grooves left in the skirts at all. I fretted over reusing them for a few days and not willing to spend the 700/800 dollars at the time for new pistons I bought new rings and had the machine shop tighten up the final cylinder clearances about .005 thousands and with a new block reassembled it all. It not only ran fine but it was about .15 quicker than it was before. I didn't like doing it but it was the only game I had available to me at the time so I did and it worked out fine. The original block was a 71 302 block and the new block was a E7TE. One thing I like about running the later blocks is the lifter bores are taller and support the solid roller lifter better than the earlier blocks do. I wish the op much success in his/her build. Go get'em.