LQ9 used factory pistons were brought to a machinist and he said Measured from the pin to the tip of the skirt of the piston the measurements vary from .003 to .005 to .007 off.

I am not sure what this is, but can someone school me on what this would do and how this affects a motor? I understand that if this was WAY off but the length of the skirt being that little off?

Thanks

 

The skirt just keeps the piston for rocking inside the bore. I wouldn't be concerned with that small amount of variance, especially on a stock piece. Now if he had said that those variances were from the crown or top of the piston, then I would be a little concerned. As that measurement would affect the deck height of the piston (piston to head clearance, and compression ratio measurements).

 

its kinda hard to understand if your not a machinist or not familiar with numbers like that but il put it this way .010 is the thickness of a piece of a notebook paper!! i wouldnt worry about it.

 

A piece of notebook paper is about .004". Maybe Two sheets.

 

GM's piston slap


what are you building? If you're boring it out, you can't use the factory pistons

 

My LQ9 6.0 is ready to go.... This is to do with a used set of LQ9 pistons I sold

I do not want any issues with the person buying them, but they are used, and I see no reason why they can't be used again.

 

they're good for a stock bore, and new rings

 

I don't think the piston being a few thousandths shorter would make piston slap. If it got more narrow at the bottom of the skirt I would say it might cause piston slap.

 

These are the updated 03+ pistons with the coating on the skirts to prevent piston slap

 

never mind, they'll work