Piston in the hole

[bbarrett]

I checked one of my 4.0s today that i believe has never been into since it left the factory, The bearings have the manufacturing date the same as the year model of the motor. So if someone did tear into this engine, (Which other signs says no) they didn't replace the bearings. So i decided i would check the stock deck height. Its 50 thousands down in the hole. Now according to all my research these shouldn't be but 20 thousands or there about. Whats also funny is the pistons have the 677P STD etched into the top of the pistons. Did Jeep use sealed power pistons from the factory? It was very interesting to me to find this. I drove this motor before i tore it down and there was no pinging or rattle in any situation i could put the jeep in. Has anyone else measured what was stock from the factory and found this? Although i cant say 100% this motor has never been into, I can say that from the small things that usually get left off or not put back, It looks as though This motor has never been torn down. It is some food for thought on quench height settings.

[Flash]

What year is it?
Mine spare eng is a 89 and the piston set .021 below deck.

[Cheromaniac]

AFAIK, the 677P pistons were not standard on the 4.0 so they must have been changed at some point.

[bbarrett]

AFAIK, the 677P pistons were not standard on the 4.0 so they must have been changed at some point.

They may have been, But if they were they didn't changed the bearings. There was also other things that says that the motor has never been tampered with, But as i said there is no way i can prove either way. But my main point was i did drive the motor ( rather hard) With no pinging or other ill effects. Although i didn't put many miles on it, it was a strong running motor.