I have a customers 2000 Vette in my shop. It's a Lingenfelter 403 C.I. twin turbo conversion. He lost oil pressure. I pulled the engine and tore it down. The #2 cam bearing is wiped out and was back far enough to expose the oil grove in the block and wear a notch in it from the lifter. It doesn't look like it spun and when I removed it, there was plenty of press fit. The pistons are scuffed bad on the skirts. The rest of the engine looks good. The crank is perfect. Rod bearings show minor wear. Any ideas what could have caused it. I would like to find the cause to prevent it from happening again.
Thanks
Bob

 

I'm sure the 2 turbos werent helping matters

 

how many miles did the engine make it? did anyone change cams recently? maybe it got bumped and pushed back on install? otherwise it walked from the vibrations once it wiped out, and the 2 turbos probably put a big strain on the oil system. make sure its got a good oil pump and maybe go dry sump so the engine wont starve. the turbos take up oil capacity once everythings running, some people have issues with oil psi dropping under decel, depending on baffling in the pan. add in the lower volume of oil if its not factored in, and once in a while it might starve. had that problem in a olds 455.

 

same thing here http://www.ls1.com/forums/showthread.php?t=14784

 

I've heard of this before, do a search on this site. I know this sounds like a patch but i would use locktite on the cam bearings to be sure they don't move in high HP ls1 applications. Do you have pics of the cam bearing? If it was wiped out could it have been fitted too tight in the 1st place and overheated?

 

Sounds like the same problem. I'm a little paranoid about putting this thing together without knowing what caused it. There must be others.

 

The bearing that moved was wiped out. Over .015 clearance. The only thing I can come up with is that once the bearing wears out, the cam flops around enough to pound on it and work it out.

 

I'll try and get some pictures posted.

 

I think once its wore thin they move easily out of place. But honestly I think there is something else going on with these aluminum blocks with the cam bearings walking. I personally have used the locktite to keep bearings in place, if they move with locktite on them something has to be extremely wrong.

Did you check the bore alignment? maybe the block has a core shift. This will cause hell on the bearings but the mains would fail too.

 

The cam bore alignment is good and there's no damage to the main bearings. Since aluminum expands more than iron, could the cam bore get large enough to take away most of the press fit when the temp gets high. I do plan on using locktite. The engine doesn't show signs of overheating. It's a PITA getting the engine out and I only want to do this once. Thanks for the help, it's always good to hear other thoughts.

 

Bob,

Do you know or have you measured the #2 cam bearing bore diameter and the cam journal diameter(s)?

Journal diameter 2.164-2.166 per GM specs.

Bottom of page 93 gives Clevite's specs:

http://mahleclevite.com/publications/EB-10-07.pdf

Bearing mfr. and part #?

Roy