Generation IV Internal Engine - Cam bearing...do I really need to replace?

Assmebled short and just noticed the cam bearings on this L76 motor. I'm reading this is normal?
http://i294.photobucket.com/albums/mm112/LSxChevelle/IMG_20120314_165444.jpg
http://i294.photobucket.com/albums/mm112/LSxChevelle/IMG_20120314_165434.jpg

I'm not 100% sure on the L76. However the front cam bearing looked like this on my LM7. Asked around on pt.net and they all said it's completely normal. Threw my new cam in and it's got about 10k on it with no issues.

My L92 looked like this also and were the #1 reason I tore apart the engine and rebuilt it. I suspect the AFM lifters contribute to the bottom wear with their extra spring pressures on the cam to keep them in contact when AFM is engaged..

I don't like doing things twice so I replaced, YMMV..

I did read a thread where a guy saw copper on his brand new crate motor....interesting. Line bored after bearings installed?

I wouldn't be as worried about cam bearings as I would of any other bearings in the bottom end, in fact, I don't think I've ever seen the cam bearings (at least the front ones) look "good" on any small or big block I've ever opened up...but man, be cleaner!!! There's a lot of dirt in there on the block casting surfaces...stuff like that will contribute to an early failure.

My 65k LS has copper showing as well. Mines more on the side than the bottom. But, the way i see it, you can buy a set of Dura-Bond bearings for ~$40. thats pretty cheap insurance if you ask me....Id go ahead and replace them since your already that far...

Those are worn out, and it's quite common on these motors - I always use the Durabond Teflon coated bearings. If not now, it will soon cause a pressure drop across the whole system if you don't replace those.

As was said, you need to really spend some cleaning time in there.

Actually they all look like that even new on many GM blocks. They are probably fine. you can measure the clearance like we do if you are worried.

Actually they all look like that even new on many GM blocks. They are probably fine. you can measure the clearance like we do if you are worried.

Erik - what clearance do you look for on the cam bearings? Thanks!

Actually they all look like that even new on many GM blocks. They are probably fine. you can measure the clearance like we do if you are worried.


Unless that picture is tricking me, there's a wear ridge on the backside of that front bearing, and I've only seen a couple low mile blocks with a similar look to the bearings - they measured over .004".

Erik - what clearance do you look for on the cam bearings? Thanks!

I think GM spec is crazy like .001-.006 but about .003 is good. I've never really seen cam bearing problems myself unless the cam is bent or teh cam is large and tight clearance

Unless that picture is tricking me, there's a wear ridge on the backside of that front bearing, and I've only seen a couple low mile blocks with a similar look to the bearings - they measured over .004".

It probably does have a little wear but they really do always seem to look like that for some reason on the GM OEM bearings. They look worn out when they are right out of the crate brand new!?!

Way, way back in early '02 I had a non-LS shop do a cam swap for me on my T/A at 10k miles. They called mid-process saying 2 of the cam bearings had copper showing and needed to be replaced (hell you can probably search my s/n and find that thread) and yanked the motor out. It was not much wear showing, less than the OP's pic, but I was young and dumb and had them do it. Most on here thought nothing of the wear, and watching threads like this I've come to find over the years it's the norm for an LS with virtually any miles on it. I can only recall of like 1 person ever having a cam bearing spin on them. Needless to say my shop experience chapped my ass pretty bad and I've done virtually all my own work since then.

Copper showing on brand new cam bearings is normal due to line hone at GM (I was told by a very reputable shop in Detroit). Looking around their shop was a few brand new LS7 blocks and they all had the same condition. I wouldn't touch the bearings unless you absolutely have to. There are multiple horror stories on this board about incorrectly installed aftermarket bearings causing them to spin.