Torqueshaft

Which journal was it ?

Ratical

iTrader: (82)

I wish I would have know about this potential issue 6 months ago. I would have pinned mine just to be safe. Not taking it all back apart now so I guess I will just cross my fingers that I do not have one of the problem children. I did give my cam to the machine shop just to make sure there were proper clearances, so hopefully he did what I asked and checked it.

ZONES89RS

iTrader: (25)

Very interesting subject. I'm a junkyard builder for the majority of every swap I've done. Or replacement for that matter. I have yet to have a problem with a gen III or IV that had no cam change. The one we did have a issue with was in a string of bad luck my buddy had that was trying to use a 6 liter for a car I sold him. First was a broken head bolt. He just sold that one to a guy that said he could fix it. Got another and as we were installing a new cam in to the used short block, the second to last cam bearing pushed out. Perhaps it had spun a little and what not? Ended up having to take the engine apart just to replace it and went forward with cleaning the block, checking rods, had to resize 2. Put it back together and ran the fire out of it for a few hundred miles.

Took it apart so he could sell the chassis, threw a stock LS1 cam in the same engine, dropped it in his truck and drove the **** out of it for 7-8k miles and the truck got hit. Threw the engine in another older chassis truck and it started knocking. Not sure how that happened, of from impact or what, but he was tired of it and sold the engine as is.

I have had a GEN 1 I was building push the second to last bearing out as well. This was fresh from the machine shop. And the bastards charged me a full set of cam bearings to fix the ****. Not sure why they had to do that. But the cam would not go in and I tried to bump it in by slowly tapping it with a dead blow.

Otherwise, this must be rare as I have not had a problem with one spinning while running to my knowledge. I will update if the one in my 2004 3/4 ton happens to look bad. It started tapping and I drive it till it just decided to lock up. Oil pressure gauge never worked in it so I could not say how long it may have had the ability to warn me of a pending pressure problem.

All the cam swaps I have done have used single springs so I have never had a problem with high spring pressure like some that could be a problem as mentioned.

VintageCamaroChris

iTrader: (3)

it is the one dead center.

neat

I just went and measured:

Stock cam, 130K, front - 2.1640
130K mile stock cam bearing, still installed, copper showing - 2.1685
Comp cam, front, new - 2.1640

That was all done with a vernier caliper, my bore mic is at work so I can't check the bore on the other cam bearings with what I have here at the house.

That being said, with the worn factory bearing there is about 3.5 thousandths of bearing clearance. That seems a little high to me. Even at 1.5 thou per inch of bearing diameter, it should only be 3.15.

Given the issues though, I wonder if the extra bearing clearance is a good thing?

kingtal0n

iTrader: (1)

I am curious which journal receives oil last? I am guessing all the cam bearings run the same clearance, but wouldn't it make sense to give the first bearings which receive oil a slightly larger clearance than the final ones? Does the Factory Service Manual specify anything unique with respect to cam bearings?

Striker289

iTrader: (1)

I replaced a motor in one of my fathers work trucks with 120k. 09 ly6 6.0 Cam bearing walked out, scored the lifter then the lifter got stuck in the bore. Was going to rebuilt it but sold it because i couldnt afford machining costs at the time.

A_VAS

iTrader: (16)

6.0 LS2 alum block here, #2 cam brg walked out on me. Was hitting the lifter body and had a nice 1/2 circle cut into the bearing...actually the lifter body held it in place for a while I'm guessing. Once it came all the way out lost oil pressure and prompted me to tear it down.
took about 2-3k street miles for it to come out

the cam did not seize to the bearing...or spin it. The bearing walked forward basically. Not enough interference fit is my observation..Speed Pro aftermarket cam bearing on a fresh block rebuild. when I knocked remaining cam bearings out, they had very little press fit. The alum block grows when warm...bearing not so much.

my solution since has been a light slick of the Green Loctite product on the back of all 5 cam bearings...and make sure when they go in they take a good bit of force to get in. If they go in with light blows on the driver, then the interference is not adequate and I start checking dims. Durabonds vs. Speed Pro Sealed power etc they all measure a tick different

stevieturbo

I was advised not to loctite.

I just pinned them...they'll never move again.

Kawabuggy

iTrader: (1)

Count me in that group that has taken apart factory motors for the purpose of rebuilding/installing new bearings and have found #2 cam bearing has walked out of the bore. I've seen it more than once. No cam swap had been done on either of these engines previously.... All factory parts. These were both cast iron 6.0 blocks, and both were gen 3's. One of those motors was rebuilt with new cam bearings, and has been in my truck for the past 4 years or so (don't remember how long ago I put it in)..