killernoodle

Hey guys, im taking the motor in my V apart because it was making a knocking noise and would like your opinion about piston rocking. I'm going to check the lifters and everything else, I just wanted to make sure I had the issue nailed down . the skirts of the pistons have substantial wear and they fit loose on the bore at the bottom of the skirt, then get tighter piston to wall clearances towards the rings. I was able to get a .008" feeler in at the bottom of the skirt in the piston I took out, but that feeler wouldn't fit at the top of the skirt.


These are diamond 3.905" pistons in an LS1 block. I'm going to get some pics of the wear on the skirts and bores and post those too tonight.

Do you guys think the piston to wall clearance is the source of my knocking issue? Oil pressures were great and all the valvetrain was new. Every piston in the motor rocked like this, some more than others.

KCS

iTrader: (20)

The pistons are supposed to be barrel shaped so they will get tighter between the rings and bottom of the skirt. Totally normal.

farmington

iTrader: (14)

a forged piston motor will ALWAYS have more piston noise than a cast piston motor due to the larger piston to wall clearances. The forged piston will expand more when it gets warm so when up to temp the noise should go down.

RockinWs6

Looks like way too much from here. Only way to know is to pull them and measure the pistons and the bores. Looks to me like it has double the proper clearance. It will sound like a box of rocks even hot if it is.