This is like a 2009 1500 with flex fuel 5.3 LMG

 

Having done near 100 warranty fixes for the GM shops in phx area. Most all of the piston noise is from the bore being to big for said piston. I had to talk to a GM engineer when I was supplied with pistons from the dealership to bore and hone for warranty replacement.
It took several days for said engineers to come up with an answer. The final result was .0008 to.001. Measured at the pin centerline. Seems to have worked as there have been no comebacks

 

I've got access to Alldata and went through the factory specifications for an '09 LMG 5.3L, didn't find any specific piston to bore clearance specifications. The bore is listed at "3.779 to 3.78". There are dozens of specifications for pin to piston and rings to pistons but nothing relating bore to piston.

 

Production - −0.0014 to +0.0006 in
With coating worn off - 0.0028 in

This is from GM SI

 

Am I reading that right? The bore can be .0014 smaller than the piston?

 

I have only checked one piston and one hole. It is -.0005 new block new piston. This is for a turbo I thought this ant going to work. I'll check them and see what I got.

Thanks for the replies

 

How does a piston go in a hole that is smaller than the piston itself?

 

Cylinder 3.7794-3.7798

Pistons 3.7791-3.7795

I did pick up the largest piston and the smallest hole t first. But was off on my -.0005 for that combo. But still DANG.

Guess I'll try to hone some clearance in it.