I have an 09 LC9 5.3 Aluminum block.

im doing a rebuild because its 255k miles and i went to do thw AFM delete and the cam bearings are worn out. So i oulled the engine and Amy doing a complete refresh.

Anyway, The issue im having is that my #1 and #5 cam bores are using the ch10 style bore diameter of 2.326-2.328

2,3,and 4 all use the larger diameter bore of 2.348

I can only find 1 bearing that is the small bore with the wide bearing and its only a single bearing and no set that I have seen uses this bearing. Ac Delco number 19260875.

Has anyone else seen is problem or have a solution to it? I ask because that 1 bearing is $50 locally and $35 from summit etc.

Should I run the older ch10 style narrow bearing in its place? Or should I spend $100 on 2 bearings?

 

None of the Gen 4 stuff used ch10 from my understanding it shoudl be ch23/25 or equivalent. They should all very in size from the outside 1/5, 2/4 and 3 being the smallest. 1/2/3 go in from front of engine and 4/5 rear. You should deburr any marks left by the old bearings in the aluminum as it will be a riser.

Has your block been modified or something?

 

LC9 cam bearing bores SHOULD be-
bore 1/5 - 2.346
bore 2/4 - 2.326
bore 3 - 2.307

 

Not modified at all that I know of. I've only had the truck for about 2.5 years.

I will go check thw bores for burrs in just a few.

 

I have been researching all morning and this is what is throwing me off. The OD of the old 1 and 5 bearing is 2.324-2.326

The bore on 1 and 5 is 2.328 on my aluminum 5.3

The bore of bearing numbers 2. 3 and 4 are correct for the 2.348 bearings.

I cant find any information about why bearings 1 and 5 would be smaller. It's weird.

The new bearing I have are engine tech CC433W and it claims that all bores should be 2.348

when i measure the OD of the old bearings, they are .015 to .020 smaller than the new bearings.

 

The end bore needs to be larger than the inner bores with the center bore smaller than the rest.

 

I realize that is how it should be...but it is not.

I will go recheck it all to be %100 positive.

 

I got the specs from Summit's LS database for an LC9.

 

Is suppose it could be a factory blem in the block machining so they patched it up with an oversize. Idk

 

Ok so I went a rechecked thw bores and recalibrate my bore Guage and digital calipers. I think I didn't have the bore Guage set right because it checked out correct.

So I went ahead and installed thw bearings I have. The #1 was tight and left some burs so I have some clean up to do but they are all in now and done. Once it cools off in a couple hours I will clean them up and then check the cam fitment.

 

I know on my spare gen 4 5.3 they came out hard and went in hard lol. I've thought about setting the block outside in the sun to help next time. I use the summit LS bearing tool and it works well. also note you can run the wider 25 bearing in a 23 application if desired.

 

Hopefully, when you were driving in the new bearings you were lubing the block bore with assembly lube, and also the O/D of the bearings as well. You cannot run them in dry, or they will gall, and pull a bunch of metal off... Ask me how I know... I made that mistake ONCE... and only ONCE. After that, the block bores are coated and dripping in engine assembly lube as well as the bearings.. They go in like butter that way..

 

IDK I've heard both ways. The old ones came out harder than the new ones went in, but a lot of that is the edge where the bearing rides gets built up and you end up dragging the bearing over it. Need to clean up that material and where the parting line of a stock bearing scars the aluminum block.

 

I'll say this; the fewer times you change the cam bearings on an aluminum block, the better. I'll also add that the next time I install, or pay to have someone install, the cam bearings, I'm going to stake them on both sides. This is because I lost an engine due to the #5 bearing shell walking forward and exposing the oil feed hole, resulting in losing all oil pressure, and catastrophically ruining my engine. Ifs and buts, but priority main oiling was the standard of the industry for nearly 100 years, for good reason. If that happened in a SBC, most of the motor would've been OK. Oiling the mains and rods last in the LS architecture is NOT my idea of a good design, and is one of the few complaints I have against the LS engines.......

 

Was that an aluminum block it walked out on? I've seen and heard of quite a few iron 6.0 having that happen just never aluminum.