07NBSChevy

Hey guys, doing a cam swap in my 2007.5 NNBS Silverado with a Gen 4 5.3 LMG. I am also removing all the AFM/DOD hardware. So I have the engine on a stand and have it stripped down to a short block. After cleaning up the block and all parts, I went ahead and removed the stock cam, went to inspect the bearings and noticed on all 5 bearings it had some sort of, what looked like, machine marks. The marks were above the oil holes on the top portion of the bearings and all the marks were all in the same location and looked the same as the next bearing. I can also feel a texture difference were the marks are, now the texture is smooth and there is no grooves, it just doesnt feel the same as the bottom portion. I have asked a few local LS engine techs here and they say those marks are for oil purposes. There is no visible copper, all the pil feed holes are ligned up and for the most part appear in good shape. I am really hoping so because I had no plans to change the bearings. The truck only has a tad over 100k miles, hot idle oil pressure is 25PSI and anything above 2k rpm it maintains 45-50 PSI. The old cam journals are smooth and have no visible markings/wear on them. If it matters this is a Iron block and all the internals are original from the factory and never been messed with. I will post up pictures and hopefully you guys say they are good to go.

Beatdown Z

iTrader: (18)

They look better than the bearings in all the engines I've cam swapped...

slvrram

Isn't that the truth.

In a perfect world, I'd replace them. I don't suspect you'll have any problems using them though.

MrHorsepowerLSx

iTrader: (13)

They look fine to me, someone else on here also posted something similar to your bearings, but the bearings looked very worn and copper was showing. Turned out that is what they looked like directly from GM, they said that the "marks" in the bearings were from the machine process to make the bearing perfectly true and round. But as also stated, the bearings looked better then some i have seen as well. Good luck with your build!

07NBSChevy

I had a GM Engine Tech look at it and he said the same thing. It is the Machine process they do after they are installed, similar to Line Boring I guess. He said it also aids in oiling. The marks are very smooth to the touch but had a different texture to it. He also measured them out and said they are well within spec and sees no need to change them, but.....did say it is always recommend to change cam bearings when swapping a cam according to GM. I think he also said it is something they are doing on the Gen 4 and newer Truck engines from the factory. It is a big relief because I really did not want to change them out and remove the crank, rods, pistons and then have to swap out those bearings and get new Main and rod bolts.


Thanks guys.