Hello,

Background: fresh cam bearings fresh install by trusted machine shop. Ls6 cam is new, had been installed and removed, never fired/ran. It was hard to remove when we disassembled the block.

Now I am trying to install an ls6 cam into an aluminum 5.3. The cam gets stuck in the second cam bearing. It just will not move or spin. I then tried installing a friends comp cam that has been ran and it slid right in. Not quite sure what the issue is here?

Please help,

Noah

 

Have you measured the journal diameters?

 

I did not. I trusted the machine shop/oem cam.

I wanted some ideas from here before I tear the crank/pistons out. I guess that's what I'll be doing Monday

 

A rod would have to smack the cam very hard to bend it. And the mark would be very noticeable Im sure its a bearing journal issue

 

Cam bearings wasnt install in proper order buddy of mine had same problem

 

Alright I'll take bottom end apart and measure the bearings

 

"I trusted the machine shop/oem cam."

Take it back to them, and let them correct it???

 

I ran into this exact same problem before (new cam bearings with OEM LS6 cam). You will need different cam bearings. Don't ask me why but aftermarket cam bearings are slightly too small for OEM cams but work fine with aftermarket cams. Take the block and the cam to the machine shop and have them install the correct cam bearings.

 

That the samething the machine shop told my buddy bout aftermarket cam bearings but came to find out they where install in wrong order alot of these old school machine shops dont know to much bout this ls stuff when u open the cam bearing box the box have what postion the bearing should be install the bearing have numbers on them so u want mix them up

 

the actual cam bearing clearance needs to be measured. When I installed my aftermarket cam bearings, the clearance was about 0.0005" or less in some places. I had to open up the clearance with some 2000# sandpaper. 0.002"-0.006" is good clearance for cams.

Another thing, if the engine is hanging off an engine stand, there may be some slight sag in the block. Flip the engine upside-down and wait a couple minutes, then try to insert the cam again. This has worked for me in the past.

 

I have read in the past that the cam bearings are align honed by GM, can anyone confirm this?

 

That is correct sir.

 

have you checked the cam for out of round?