severe piston skirt wear. Major problem?

[Zboy]

I removed the pistons and rods from my spare engine the other day. The pistons on the back bank ( closest to the firewall) Have some pretty severe wear on the thrust side of the piston skirt. The non thrust side is virtually perfect as are the other three pistons on the front bank. The bores all cleaned up nicely with a medium grit hone. No major damage to the cylinders. Is this type of wear common on a 6/60? Or do I have an issue somewhere? Next, can I use three pistons out of the front bank of the junk engine I have? ( provided they are in useable shape) How is the factory balance on the piston\rod assemblies? Am I going to have issues with vibration by switching assemblies or did GM do a decent job of makin g parts that are very close to each other balance wise? I know swapping parts like this is not a good way to do things, but I don' t have a choice here. No money for new pistons. I'm in way over my head cash wise, and this car just needs to be done.

[SappySE107]

You can't use the pistons from the front bank on the rear bank. Im not aware of a common problem with wear like that either as the only DOHC ive torn down that had any severe wear problems was one that had bad bearings and was generally not taken care of. As far as balance goes, GM doesn't balance anything so any rods/pistons you can swap should be as good as another.

[series8217]

Am I going to have issues with vibration by switching assemblies or did GM do a decent job of makin g parts that are very close to each other balance wise?

hhehehehehehe.

Yeah GM doesn't do jack shit. I recommend at least matching the rods if you have a good scale, its still better than nothing. IIRC some of mine were off by 8 grams!

[Juglenaut]

I think it is a tolerance, crank to rod alinement or crank rod to piston issue.

Possibly even a lean condition over time can cause this, more profound if the engine had this condition form birth. Oil distribution problem. Incorrect tolerance piston rings for cylinder bore, worn piston rings, piston wobble. Crank in block out of alinement tolerance.

If I saw waer like that I would not stick money into it as a long block, my opinion is it needs to be torn down and checked for tolerances all over.