steel_3d

Has anyone had experience putting cam bearings in?

My shop put in a GM set I got, and the #2 was way too tight, like -0.010 clearance. Cam wouldn't go in. After taking out #2, the other bearings were a bit tight as well, and I couldn't spin the cam by hand, needed a wrench.

I think the OD of the #2 was .005-.010 too big, which ended up squeezing the inside diameter.

The shop's tool really sucks as well. The lip is not quite wide enough and a little worn down, so it likes to dig into the side of the bearing and bunch it up. ****** shops...

Then I tried a set of race bearings the shop had, but the OD on those is also .005-.010 too big. Shop messed up the #3 trying to get it in, and even after I cleaned it up and put it back in, it was way too tight. Tried #4 and it wouldn't even start. I didn't wanna jam it.

The holes in the block are exactly the right spec, not tapered or out of round.

The bottoms of the bores are a little gouged because of the **** gm split design that gouges the block. But the gouges are going into the block, not out, so I don't think they're squeezing the bearings. Besides, .010 is a huge amount.

The bearings seem like the wrong specs.

Note, all the bearings slid nicely onto the cam journals when new, with plenty of play.

Note also, that the GM bearings came with huge yellow spots, more than even my 115k mile bearings that I thought were worn. They looked really ugly, like they weren't even new. Is it normal to see yellow spots on new GM bearings??

Any tips? I'm pulling my hair out here...

steel_3d

Before anyone asks, yes I know the LS3 bearing ODs are staggered and are numbered 1,2,3.

And yes, I got the right bearings, they're just not what they're specced to be.

The cam is the stock LS3 I pulled out with perfect 55mm journals, absolutely zero marks on them. Of course the journals wouldn't grow in any event

george g

iTrader: (12)

I had the direct opposite my bearings were too loose,and I had to get thicker bearings and have them line honed to size.Might see if they can do the same for you since your bearings are already tight.

87silverbullet

iTrader: (11)

Op, I had the same problem you did in my block. My engine builder was putting in clevite cam bearings and my cam wouldnt go in. He tried the gm ones and still a no go. We ended up putting in durabond cam bearings after talking with a few guys on here and with the help of Matt@TexasSpeed. Cam slid in like butter afterwards.

Gray86hatch

iTrader: (83)

Durabond and the proper install tool.

Tim

RezinTexas

sorry to hear about your troubles.

here is a link for a tool that someone posted yesterday. I do not have any feedback on using it, however.

http://carshop.carshopinc.com/produc...24334/CSP10900

KCS

iTrader: (20)

I had that problem with the Durabond cam bearings and a Comp cam. I measured like I would the main or rod bearings and found the #3 bearing had .0005" clearance and the rest had .001 - .0015", which I thought was really tight. I took my cam to a local crank grinder that everyone in Houston uses and had the journals ground to get more clearance. Problem solved and cost about as much as another set of bearings.

steel_3d

Durabond (EDIT: Clevite), that's the one I'm using. The ODs are pretty damn big, .005-.010 bigger than what it says on their spec sheet. I don't think that's correct. Is the interference fit supposed to be THAT negative in your experience?

I'm measuring all clearances with a dial bore gauge, so I can get pretty exact.

I was thinking of honing the block a bit to make them fit, but that's a pretty big ordeal again, and kinda precludes stock bearings in the future.

I'll try another shop today, if I can reach anyone.

Thanks for your input.

steel_3d

And are new GM bearings supposed to have large yellow spots, or did they send me junk bearings?

steel_3d

Got the cam in. The Clevites went in with a better tool. Ended up replacing the messed up #3 with a bearing from another set. Hit the bores a bit with a ball hone, to smooth out the scoring caused by the stock bearings. Also polished the cam journals, but that probably didn't change anything. Apparently the 5-10 thou interference on the OD was not that abnormal.

On the other hand, a set of coated clevites we tried did not work. The #3 got tight again.

The only problem now is that the cam doesn't turn by hand, only with a wrench. Turns pretty easy with a wrench, though. I'm hoping a little scotch brite will open them up enough.

Any input? Should I be worried about spun bearings, or will they sort themselves out, being babbitt?

steel_3d

I massaged the #2 for quite a while with scotch brite and even 600 grit sandpaper, concentrating on the high spots around the oiling holes, and I got the cam to turn by hand. The clearances on the bearings are .0015-.004 depending on the hole. I doubt I would get spun bearings at this clearance...

RezinTexas

0.0015 is probably ok, I would try to open it up a little more if you had the chance.

I used 600 grit paper on mine also, with success.