Cause of cam bearing wear?
02-02-2006, 02:21 PM
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Cause of cam bearing wear? Any ideas on what might have caused my front cam bearing to look like this?
The scratches might have been my fault but that doesn't explain how it got worn down to the brass. Car only has 22,000 miles on it. Stock internals. About 1,000 1/4-mile passes.
The scratches might have been my fault but that doesn't explain how it got worn down to the brass. Car only has 22,000 miles on it. Stock internals. About 1,000 1/4-mile passes.
02-03-2006, 12:36 PM
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Actually, I was very careful to follow the recommended break-in procedures exactly. And, I didn’t make my first pass in it until I had 1,000 miles on the odometer.
Since I posted this I have done some more studying of how it looks. Now I’m thinking that maybe the cam bearing spun or was not installed correctly at the factory. Here is a straight-on shot (more or less).
I assume the two oil holes are supposed to line up symmetrically with the block. But you can see that they don’t. They are 2 or 3 degrees counterclockwise. If I put an awl through the right hole, I can feel that it is open behind it so I assume it is not blocked. But it feels like solid metal behind the left hole. So, I think its likely that the bearing was not getting sufficient oil to it. Yes? No? Opinions, please.
Since I posted this I have done some more studying of how it looks. Now I’m thinking that maybe the cam bearing spun or was not installed correctly at the factory. Here is a straight-on shot (more or less).
I assume the two oil holes are supposed to line up symmetrically with the block. But you can see that they don’t. They are 2 or 3 degrees counterclockwise. If I put an awl through the right hole, I can feel that it is open behind it so I assume it is not blocked. But it feels like solid metal behind the left hole. So, I think its likely that the bearing was not getting sufficient oil to it. Yes? No? Opinions, please.
02-03-2006, 01:36 PM
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I am so jelous of those lifter tools you have there in your picture. I need a set of those but dont want to spend $85 on them. Call me cheap, I dont care. 
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02-03-2006, 01:58 PM
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Originally Posted by Robinator
I am so jelous of those lifter tools you have there in your picture. I need a set of those but dont want to spend $85 on them. Call me cheap, I dont care.
I thought it would be just a 24 hour loan. But then I hit this snag with the bearings. I told him to let me know if he needs them back before I figure out what to with the bearings. If he does, I will put the old cam back in temporarily.
And the tool is great.
02-16-2006, 10:09 AM
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This might not be a problem after all.
First, I have now learned that there is only ONE oil galley for each bearing. Also they are relatively large and the holes don’t need to be perfectly even to line up. That is why I found that one hole was blocked and the other wasn’t. It’s all perfectly normal.
Second, I sent a photo to Horsepower Engineering (LS1 and LS2 engines and a site sponsor). Here is what he said:
BTW, I bought a borescope which arrived last Friday. All five cam bearings have the same problem – they are worn down to the brass in roughly the 4:30 and 7:30 positions (directly opposite the pushrod ends). It is more pronounced on the driver’s side. No scratches or rough spots.
First, I have now learned that there is only ONE oil galley for each bearing. Also they are relatively large and the holes don’t need to be perfectly even to line up. That is why I found that one hole was blocked and the other wasn’t. It’s all perfectly normal.
Second, I sent a photo to Horsepower Engineering (LS1 and LS2 engines and a site sponsor). Here is what he said:
Originally Posted by Ken at HPE
Ed,
Believe it or not the OEM cam bearing look like that even when they are practically new. I will try and send you a pic myself of some new 6.0 blocks because they are very similar and have patches of copper/brass showing through even when they are absolutely brand new! Basically they look like crap but they work just fine. Some are worse looking than others too so it's hard to tell if your's are really that bad if you know what I mean. You could get a dial bore gauge and measure them for out of round but you might be surprised to find that they are possibly alright.
Basically any time you take the cam in or out you get the scratches so don't worry too much about that. Also Chevrolet/GM has a huge range of oil clearance on the cam bearings from about .001-.006 so they are not a highly critical item in the first place. As long as the cam spins over smoothly you are usually fine and it doesn't hurt to check the oil clearance by setting a dial bore gauge to the size of your cam journals and then seeing how much bigger the inner diameters of the cam bearings are. Basically though if you can get the cam in and out of the block and it spins fine you are set. You could also set the cam on some V-blocks and spin it with an indicator if you think it may be bent.
Believe it or not the OEM cam bearing look like that even when they are practically new. I will try and send you a pic myself of some new 6.0 blocks because they are very similar and have patches of copper/brass showing through even when they are absolutely brand new! Basically they look like crap but they work just fine. Some are worse looking than others too so it's hard to tell if your's are really that bad if you know what I mean. You could get a dial bore gauge and measure them for out of round but you might be surprised to find that they are possibly alright.
Basically any time you take the cam in or out you get the scratches so don't worry too much about that. Also Chevrolet/GM has a huge range of oil clearance on the cam bearings from about .001-.006 so they are not a highly critical item in the first place. As long as the cam spins over smoothly you are usually fine and it doesn't hurt to check the oil clearance by setting a dial bore gauge to the size of your cam journals and then seeing how much bigger the inner diameters of the cam bearings are. Basically though if you can get the cam in and out of the block and it spins fine you are set. You could also set the cam on some V-blocks and spin it with an indicator if you think it may be bent.
02-16-2006, 10:22 AM
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Thanks MrED thats good news, as i had the same marks on my bearings. I didnt worry too much about it beacuse i had measured everything up and it was all in spec per the GM service manual.
Thanks
Thanks
02-16-2006, 10:30 AM
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Originally Posted by Mr Ed
This might not be a problem after all.
First, I have now learned that there is only ONE oil galley for each bearing. Also they are relatively large and the holes don’t need to be perfectly even to line up. That is why I found that one hole was blocked and the other wasn’t. It’s all perfectly normal.
Second, I sent a photo to Horsepower Engineering (LS1 and LS2 engines and a site sponsor). Here is what he said:
BTW, I bought a borescope which arrived last Friday. All five cam bearings have the same problem – they are worn down to the brass in roughly the 4:30 and 7:30 positions (directly opposite the pushrod ends). It is more pronounced on the driver’s side. No scratches or rough spots.
First, I have now learned that there is only ONE oil galley for each bearing. Also they are relatively large and the holes don’t need to be perfectly even to line up. That is why I found that one hole was blocked and the other wasn’t. It’s all perfectly normal.
Second, I sent a photo to Horsepower Engineering (LS1 and LS2 engines and a site sponsor). Here is what he said:
BTW, I bought a borescope which arrived last Friday. All five cam bearings have the same problem – they are worn down to the brass in roughly the 4:30 and 7:30 positions (directly opposite the pushrod ends). It is more pronounced on the driver’s side. No scratches or rough spots.
