Maybe you guys can help me out in this section. We just dynoed a Vette built by another local speed shop 2000 LS1. Well it lost oil pressure and he finally got it torn apart and the cam bearing walked foward. Now we are currently working on a Z 1998 LS1 and he also had the motor done by another company and he had low oil pressure and thought it was because its a solid roller, so he shimmed the lifters, well we finally tore this motor apart and it had the same thing, 2 bearings walked foward. Now we are trying to find out if this is common or not on LS1s?

The only solution that the engine builder had right now was to instead of using assembly lube, using loctite to install them.
Any help would be appreciated.

 

Wow,
I haven't heard this before. Any way to find out which manufacturers bearings they were using... ACL, Durabond? If they're from the same company, I'd suspect the bearings.

What about the cam bearing bores? Have you guys checked them against factory specifications? Maybe a few got through that are a wee bit on the "plus" side.

-Mindgame

 

aren't the bearings supposed to be installed with the block heated on LS1s?

dunno. heard that somewhere though :-D

 

There is only two ways the brg could move.1-loose in the bore 2- The cam got hold of them,spun them and they walked. I have never put lube on the back side of brgs to install and never heard of it. Just line them up and drive um in.
There should be .004 clearance in them and the cam. I never used to check them on any SBC until I had a problem with a LT-1,now I check both the block fit and the clearance between the cam.Very expensive tool to check it with called an Intramik about 600.00 depending on size. A dial bore guage will work but it is aggravating getting a good reading and not all go to that small of a hole without buying a small one.
Green bearing mount Locktite would hold them alright.Ya would have to heat them to over 300* to get um out.

 

Ah ha! So THAT'S what does that! I, too, have built small blocks for a long time and never checked that becuase I didn't have a good tool to do it with. I never had a problem becuase of this (lucky?) but it was something I always worried about- wondering how long it was going to be before it came and bit me in the butt. For that kind of money I may tempt fate a while longer.

 

After checking a few with a small bore guage I bought and cutting my hands and arms up on the block trying to position it, I started checking around. An Intramik is not expressly made to check cam bores but bores in tight places in general.They come in all sizes and as slick as they work I am thinking of buying one for the mains and rods.
It is cheaper than the pain, blood and stitches.

 

I hear that. I gave up with a bore gague not just because it's damned inconvenient to postion in there but also becuase I could never get a consistent reading out of it with all the annoyance of getting it properly postioned. It started to feel like a measurement without real meaning becuase of all the "float" I would get from one try to the next. Finally, I did what you used to do.... shove the bearings in and forget about it.

 

Now it's to expensive not to check.

 

When the LS2 came into prodction GM changed the OD on the Cam Bearings by .010 larger. This started with the 6.0L truck blocks and last of the LS6 blocks. I have encountered it on a few 5.7L blocks as well. At first there were issues with the amount of press the bearing had and there were a few applications and instances when the bearings would walk.

I'm not certain if it was an imperfection with the bearing or the cam tunnel itself, but it is no longer an issue. Clevite has issued a part number for this and I have not seen a camshaft bearing walk since.