Sr piston rub

[Mrpopo]

Redtop sr20det, cp 9.0-1 pistons(86mm), manley rods, clevite bearings, and built head. It didn't make any noise when running. I think it's bad rings because all the bearings are perfect. Any ideas what else might cause this amount of rub?
38986

[future]

Machince shop

[Mrpopo]

Last resort yes. Everything was balanced and blueprinted before assembly.

[Firestorm]

piston clearance...your bore seems too tight. did you do it to CP's specs?

[Mrpopo]

Yes specs were followed and they moved freely in the bore(no binding). Would overheating cause rub in any way?

[jr_ss]

Overheating could've added some of that, but wouldn't have caused that. Not allowing your motor heat up to operating temperature could've done it as well. Typically forged pistons have lower tolerances than the factory cast pistons and allow more movement of the piston in the cylinder when cold. Once the piston heats up and expands you don't get the "piston" slap, which looks like this as seeing a fair amount of.

[Mrpopo]

Thanks for the info. I just measured the cylinder walls and they're like ovals. The shop that built the engine is supposed to be real good but I also found a 10mm bolt in the oil pan. Guess everyone is capable of turning out a crap job from time to time. Fortunately I have an extra block.

[TheWolf]

What you have there is a "scuffed skirt" on a piston. Either to tight on the cylinder piston clearance or to lean a mixture.

Of course the cylinders are "oval" because the piston scuffed them oval.

The piston can not be reused successfully.

[Mrpopo]

Why couldn't I reuse them? My machine shop says they're still good.

[UNITEDMASTER]

If it was "blueprinted" ask them what is the piston to bore clearance??

Are those freckles around the ring lands??

Did they use a torque plat when boring,& was each piston select fit to a specific cylinder??.

I would be willing to bet they did a on size fits all bore job, did all the pistons look like that??

[Mrpopo]

Yes one piston has freckles. The others are clean. I don't believe they did half of what they say they did. I am suing them for the loss and damages. So they aren't going to give me any details now.