Got my ass kicked by cam bearings yesterday

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clutchdust

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Rebuilding the engine in this Suburban I just picked up and I noticed the cam bearings pretty much look like shit. I really wanted to have it running this weekend so I thought "how hard can it be to replace cam bearings?" Well, I found out. For one, I don't have the cam bearing installation tool so I was "rednecking" it. So you don't make the same mistake, a seal driver is not the same as a bearing driver. Damn it.
So after some cussing and throwing and one set of cam bearings, I came up with a plan. I picked up another set of cam bearings and gave it a try. All seemed to go reasonably well. I got all five bearings in with what appeared to be minimal fuss, and yes, I did pay attention to the numbers and where they went. But when I went to actually install the cam, I could barely get it through the #2 bearing and when it went, it had shaved off a fine layer of the bearing surface. At that point, I knew I had pissed away another set of bearings but I figured I would at least run it all the way down and see how she sat. Cam went through #3 with no drama but I got to #4 and it told me in no uncertain terms to pack sand.
I don't know what the deal was but #2 and #4 just weren't worth a shit. If I remember right, those two are the same size bearings so I just don't know what's going on there. Either way, my buddy just bought the installation tool so I'll give it another stab with the right equipment and see if that solves my problem.
In the meantime, any suggestions from those of you who've actually done this?
 
God man, you stretching my memory, but all I remember is installing a set of cam bearings in a old Pontiac engine, long ago, the bottom end is something I leave to the guys used to that shit.....well for some reason the bearing were not installed, I tapped them in place, no sweat, but ONE of them shaved a bit with the cam install, but it ran about 200k miles before car disintegrated under mighty protest of rust and gloom, I dunno what happened to the engine after she started running from the cops.....they MIGHT still be chasing her......

;):hunter:
 
clutchdust said:
Rebuilding the engine in this Suburban I just picked up and I noticed the cam bearings pretty much look like shit. I really wanted to have it running this weekend so I thought "how hard can it be to replace cam bearings?" Well, I found out. For one, I don't have the cam bearing installation tool so I was "rednecking" it. So you don't make the same mistake, a seal driver is not the same as a bearing driver. Damn it.
So after some cussing and throwing and one set of cam bearings, I came up with a plan. I picked up another set of cam bearings and gave it a try. All seemed to go reasonably well. I got all five bearings in with what appeared to be minimal fuss, and yes, I did pay attention to the numbers and where they went. But when I went to actually install the cam, I could barely get it through the #2 bearing and when it went, it had shaved off a fine layer of the bearing surface. At that point, I knew I had pissed away another set of bearings but I figured I would at least run it all the way down and see how she sat. Cam went through #3 with no drama but I got to #4 and it told me in no uncertain terms to pack sand.
I don't know what the deal was but #2 and #4 just weren't worth a shit. If I remember right, those two are the same size bearings so I just don't know what's going on there. Either way, my buddy just bought the installation tool so I'll give it another stab with the right equipment and see if that solves my problem.
In the meantime, any suggestions from those of you who've actually done this?
Click to expand...

A suggestion : there were some people that informed me that GM put the bearings in before align honing. So they aligned honed he bearings. Might be good to check cam tunnel alignment. But by then your in for a complete engine rebuild.
 
Belgian1979vette said:
A suggestion : there were some people that informed me that GM put the bearings in before align honing. So they aligned honed he bearings. Might be good to check cam tunnel alignment. But by then your in for a complete engine rebuild.
Click to expand...
Man, I hope you're mistaken. Of course, I have the whole thing down now so that wouldn't even be that big a problem. I would rather just do this myself though.
 
make sure you align the oil galley holes in the bearing with the holes in the block,when you install your bearings.
 
kwplot34 said:
make sure you align the oil galley holes in the bearing with the holes in the block,when you install your bearings.
Click to expand...

Actually, that's not the best...

Even though common opinion places the cam bearing hole at the 6 o'clock position on bearings 1-4 in the SBC, it is contrary to proper oiling practice which has oil entering the bearing before reaching the point of maximum pressure. Considering that LOCAL oil pressures WITHIN the bearing may be on the order of hundreds of psi, placing the feed hole in this spot (at 6 o'clock) will overpower that of the oil supply (40 to 70 psi) when the load is the greatest. The best spot to locate that oil feed hole in the SBC, which has a groove in the block, is the 2 or 3 o'clock position (looking at the front of an upright block) which allows a wedge of oil to be pulled into the bearing to the point of maximum load.

Recently I examined one of my engines that I'd built in 1983 and noted that the machine shop had placed the oil hole at the 6 o'clock position - the cam bearings were worn considerably more than those engines I've built since in which I've installed the cam bearings with the oil holes at the 3 o'clock position (#1-4 bearings).

Here's a link to a discussion from the AERA Engine Builders Association:
http://www.mellingdurabond.com/Porta...20Bulletin.pdf
 
Although many blocks are close enough to allow installation of new cam bearings without problem, I once had a block which I'd had for many years, having bought it new from GM...
After installing new cam bearings in the proper locations (the bearings ODs are different), the #2 bearing was too tight to allow the previous cam to be reused. I tried another cam, but it was also too tight. I then pulled the #2 bearing and reinstalled the old #2 cam bearing - all was good, but I didn't want to reuse it.

After consulting with an experienced machinist, he stated that when he encounters that problem, he uses a "cutter cam", which when twisted through the tight bearing, clearances it a bit and allows proper clearance. I made one and used it - the cam fit perfectly and had no further problems.

What's a cutter cam?... Take an old cam which has good bearing journals and grind a half dozen triangular notches (about 1/8" deep) into the edge of the first journal leaving sharp edges in each notch. I know, it sounds crude, but it does work! YMMV
 
Actually, I read that GM places 2, 3 & 4 at the 5 o'clock position, and I wondered about that. And that's what I did on this one.
I'm really not pleased to hear about cutting the bearings. I wonder if that has anything to do with why it was just #2 and #4 on this one but the rest were fine. What if instead I mixed a couple sets and just used the thinner bearings on #2 and #4 instead? Seems like I'd probably want all the bearing surface I can get.
 
Just on Rock Auto and they are listing a set of .001 under bearings. Would that be exactly what those bearings are for?
 
larrywalk said:
Although many blocks are close enough to allow installation of new cam bearings without problem, I once had a block which I'd had for many years, having bought it new from GM...
After installing new cam bearings in the proper locations (the bearings ODs are different), the #2 bearing was too tight to allow the previous cam to be reused. I tried another cam, but it was also too tight. I then pulled the #2 bearing and reinstalled the old #2 cam bearing - all was good, but I didn't want to reuse it.

After consulting with an experienced machinist, he stated that when he encounters that problem, he uses a "cutter cam", which when twisted through the tight bearing, clearances it a bit and allows proper clearance. I made one and used it - the cam fit perfectly and had no further problems.

What's a cutter cam?... Take an old cam which has good bearing journals and grind a half dozen triangular notches (about 1/8" deep) into the edge of the first journal leaving sharp edges in each notch. I know, it sounds crude, but it does work! YMMV
Click to expand...

They shave the bearings a little, to align hone them.

To the OP : if you decide to have it align honed, might be a good idea to go to the larger main cam journals. They allow for a much more agressive cam without sacrificing low end and reliability.
 
Just took it to my machinist today. $75 and done. The way it's going, I'll be into it for that with one more set of bearings.
Belgian, not really that big a concern here. This is just a motor for my Suburban. The cam is a used roller from a vortec 5.7 and is the most I'll do to the inside of the motor. After this, I'll probably put on a Performer TBI intake and full exhaust just for a little better towing performance, sound and economy, but that's going to be it for this truck.
 
clutchdust said:
Just took it to my machinist today. $75 and done. The way it's going, I'll be into it for that with one more set of bearings.
Belgian, not really that big a concern here. This is just a motor for my Suburban. The cam is a used roller from a vortec 5.7 and is the most I'll do to the inside of the motor. After this, I'll probably put on a Performer TBI intake and full exhaust just for a little better towing performance, sound and economy, but that's going to be it for this truck.
Click to expand...

Sounds like you're set to go.
 
Belgian1979vette said:
clutchdust said:
Rebuilding the engine in this Suburban I just picked up and I noticed the cam bearings pretty much look like shit. I really wanted to have it running this weekend so I thought "how hard can it be to replace cam bearings?" Well, I found out. For one, I don't have the cam bearing installation tool so I was "rednecking" it. So you don't make the same mistake, a seal driver is not the same as a bearing driver. Damn it.
So after some cussing and throwing and one set of cam bearings, I came up with a plan. I picked up another set of cam bearings and gave it a try. All seemed to go reasonably well. I got all five bearings in with what appeared to be minimal fuss, and yes, I did pay attention to the numbers and where they went. But when I went to actually install the cam, I could barely get it through the #2 bearing and when it went, it had shaved off a fine layer of the bearing surface. At that point, I knew I had pissed away another set of bearings but I figured I would at least run it all the way down and see how she sat. Cam went through #3 with no drama but I got to #4 and it told me in no uncertain terms to pack sand.
I don't know what the deal was but #2 and #4 just weren't worth a shit. If I remember right, those two are the same size bearings so I just don't know what's going on there. Either way, my buddy just bought the installation tool so I'll give it another stab with the right equipment and see if that solves my problem.
In the meantime, any suggestions from those of you who've actually done this?
Click to expand...

A suggestion : there were some people that informed me that GM put the bearings in before align honing. So they aligned honed he bearings. Might be good to check cam tunnel alignment. But by then your in for a complete engine rebuild.
Click to expand...

GM line bores the cam tunnel with bearings installed to make up for their mistakes, Try to by and OEM block with out cam bearings.

I see probably 1 out of 40 blocks the cam will not go in after bearings are installed, I ckeck this as soon as I clean the block if there is an issue I am set up to blue print bore the cam tunnel.

Had one block that was off .016 on the front.

There seems to be more issues with cam tunnels on the BBC seems like one out of 8 need repairing.
 
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