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#2509881 - 06/18/18 08:23 AM Cam Bearing deburring process/tricks?
vinnyd76 Offline
super stock

Registered: 04/25/12
Posts: 951
Loc: Macomb, MI
Anyone run into an issue with installing a cam (in a small block) and have an issue with cam bearings (clearance)? I’m told some engine builders have a trick for burnishing the cam bearings by using an old cam? Any thoughts on deburring?

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#2509904 - 06/18/18 09:28 AM Re: Cam Bearing deburring process/tricks? [Re: vinnyd76]
rickseeman Offline
pro stock

Registered: 01/18/12
Posts: 1499
Loc: Little Rock, Arkansas
I've never worked on a SB, but on a Hemi it's easier to put them in one bearing at a time and then check the fit. If you put in all 5 at once and then the cam wont go in, you don't know which bearing is giving you the problem. This way you know which bearing has an issue and you can use a bearing scraper to fix the problem before you move on to the next bearing. (You probably mushroomed the end knocking it in.) You can make a cutter from an old cam. All you do is take a whizzer and cut a 1/8" deep groove across the cam journal. Then set the block on the floor vertically and use a big drill to slowly drive the cutter into the block. The cam will fit fine afterwards. I don't like this method as much because I feel it removes some bearing material that I might want to keep.
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#2509985 - 06/18/18 11:54 AM Re: Cam Bearing deburring process/tricks? [Re: vinnyd76]
FurryStump Offline
master

Registered: 10/15/04
Posts: 2515
Loc: Connecticut
Well it pains me to say, but you take an old cam and cut diagonal grooves in the bearing surface. Then oil it up and slide it in. Turn it with a wrench and remove it a bunch of times to clean out the grooves. Repeat until cam turns be hand using the timing gear without much effort. Makes me wonder why I was soooooo careful not to damage the bearings when I installed them!


Edited by FurryStump (06/18/18 11:54 AM)
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#2510050 - 06/18/18 02:39 PM Re: Cam Bearing deburring process/tricks? [Re: vinnyd76]
mopars4ever Offline
I Live Here

Registered: 01/20/03
Posts: 11094
Loc: md
I guess I have been lucky. Never had that issue on a SB.

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#2510067 - 06/18/18 03:35 PM Re: Cam Bearing deburring process/tricks? [Re: vinnyd76]
mgoblue9798 Offline
enthusiast

Registered: 03/16/10
Posts: 228
Loc: Atlanta, GA
Use a sharpie marker or machinist blue to wipe the offending bearing.
Spin the cam in it to find the high spot. If it is just on the outside edge then you can just sand out with fine grit sandpaper. Like previous poster stated they can be mushroomed on installation.

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#2510077 - 06/18/18 04:04 PM Re: Cam Bearing deburring process/tricks? [Re: mgoblue9798]
RapidRobert Offline
Circle Track

Registered: 11/20/03
Posts: 34019
Loc: Lincoln Nebraska
As said, on initial mockup, set the block on its end
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#2510138 - 06/18/18 06:51 PM Re: Cam Bearing deburring process/tricks? [Re: vinnyd76]
Frankenduster Offline
Moparts proctologist

Registered: 02/15/10
Posts: 15373
Loc: Granite Bay CA
I had a tight fit in my 440/493. It was an odd situation. I had a '509 cam in there and it seemed to spin freely. I was changing cams to a Lunati and it would not spin! I had a stock 440 cam that I cut grooves in, then I packed the grooves with bearing grease to trap the shavings. It was not a 5 minute fix...I had the cam in and out a few times to clean the grooves and reapply grease. I did it until the cam spun freely with the cam sprocket on. My machinist (Not a dedicated Mopar guy but knowledgeable about them) said this is rather common in big blocks and is actually mentioned in some Direct Connection catalogs!

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#2510160 - 06/18/18 07:31 PM Re: Cam Bearing deburring process/tricks? [Re: Frankenduster]
Cab_Burge Offline
I Win

Registered: 08/23/03
Posts: 31224
Loc: Bend,OR USA
On your deal it sounds like the Lunati was either to big on one or more of the journals or bent work shruggy
I think I would have found out why it didn't work and then probably return it for one that would fit fine work thumbs

OP, I have had some, not all of them tsk, Mopar blocks that needed a lot of work on the cam bearings to get the cams to rotate freely, a bearing knife is your friend in this case up scope The block castings are not machined properly at the factory runaway shruggy
As already mentioned install each bearing one at a time and trial fit the cam into it, once it fits fine do the next one scope wrench
I assembled a late model 440 motor home block last month that needed three cam bearings worked on to get the cam to spin freely whiney
Five or more RB and B motors before that didn't need any work on them at all shruggy


Edited by Cab_Burge (06/18/18 07:39 PM)
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#2510331 - 06/19/18 09:40 AM Re: Cam Bearing deburring process/tricks? [Re: vinnyd76]
vinnyd76 Offline
super stock

Registered: 04/25/12
Posts: 951
Loc: Macomb, MI
I reviewed the issue and the cam goes in about 95% and it struggles on the last bit to fully install. It locks up and won't allow any rotation.


Edited by vinnyd76 (06/19/18 09:41 AM)

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#2510335 - 06/19/18 09:54 AM Re: Cam Bearing deburring process/tricks? [Re: vinnyd76]
EV2Bird Offline
No more politics

Registered: 06/23/14
Posts: 4201
Loc: Kansas Roads Between 0 and 140...
Ive often been confused by this issue, and I do wonder at times if it could partially be the type/brand of bearings used?

I say this because like 15-18 years ago I bought a couple cases of the MP cam bearings so thats all I use.

I have a simple cam bearing installer, take my time and in approx 35 builds have had one cam that was tight and it was the cam, not the bearings.

As for the 95% in, I have had a couple want to go past turning with my fingers but when I put the tiny ratchet on the cam bolt and spun it a few revolutions with lube of course it quickly freed up and I never worried past that because cast core cams will flex a good bit with real heavy springs so throught the running/thrashing process I think they at times run tight on the bearings unlike a rod or main.

So VinnyD, after it gets tight (do you mean finger tight) can you use a small end wrench on the cam bolt and see if it loosens up enough before you jump through hoops?

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#2510336 - 06/19/18 09:58 AM Re: Cam Bearing deburring process/tricks? [Re: vinnyd76]
451Mopar Offline
master

Registered: 05/19/08
Posts: 4987
Loc: Aurora, Colorado
Big blocks seem to give me problems, but not so much on the small blocks. I never measured the bearing hole size in the blocks, but I will next time, just to see what they are.

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#2510371 - 06/19/18 11:39 AM Re: Cam Bearing deburring process/tricks? [Re: 451Mopar]
Cab_Burge Offline
I Win

Registered: 08/23/03
Posts: 31224
Loc: Bend,OR USA
I now test fit all the bearings onto the cam before installing them, never had a tight one yet on a cam shruggy They are all real loose on the cams so far work
OP, if your cam is a three bolt core install two or all three bolts in the cam and use a lever between them to rotate it so you can see the tight spot in which bearing that is the problem(it will shine scope) it single bolt use a wrench or socket to rotate it scope
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#2510463 - 06/19/18 04:13 PM Re: Cam Bearing deburring process/tricks? [Re: vinnyd76]
mopars4ever Offline
I Live Here

Registered: 01/20/03
Posts: 11094
Loc: md
I did have a wrong bearing in a kit before but it wouldn`t allow the cam to completely go in.

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