cam bearings too tight
#1083878
09/27/11 08:50 PM
09/27/11 08:50 PM
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Joined: Jul 2006
Posts: 4,179
California
mickm
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OP
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Joined: Jul 2006
Posts: 4,179
California
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got the block back from the machine shop, and the cam wouldn't go in. took it back, and we started playing with it. out of the block, bearings fit nicely on the cam. in the block, 3 out of the 5 were too tight. we did a lot of playing around, but finally i had to leave.
this is a mopar hemi (not world) mega block.
in the end, he found that all the holes were .0005 to .001 too small, and so were crushing the bearings when they were inserted in the block.
i brought him an old cam, and he grooved the journals on the lathe, and then inserted the cam and made 1 turn and removed it. buffed the bearings with scotchbrite, and now the cam fits like a dream!
how common is this on these blocks? i've heard of issues with these before, but all of the holes to be too small?
also the hole to the driver side head from the #4 bearing did not match perfectly, so i had him enlarge the hole in the bearing so it is completely open.
anything else i should be aware of here??
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Re: cam bearings too tight
[Re: mickm]
#1083879
09/27/11 08:53 PM
09/27/11 08:53 PM
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Joined: Jan 2003
Posts: 21,076
Niles , Ohio
therocks
oh wait.but hey.lets see.oh yeah.
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oh wait.but hey.lets see.oh yeah.
Joined: Jan 2003
Posts: 21,076
Niles , Ohio
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Ive heard quite a few that were tight.A good machinist shop should check them.Thats why they really need the cam if they install the bearings.The oil holes are the same.Some line up great some not so good.Rocky
Chrysler Firepower
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Re: cam bearings too tight
[Re: therocks]
#1083880
09/27/11 08:57 PM
09/27/11 08:57 PM
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Joined: Jul 2006
Posts: 4,179
California
mickm
OP
master
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OP
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Joined: Jul 2006
Posts: 4,179
California
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Quote:
Ive heard quite a few that were tight.A good machinist shop should check them.Thats why they really need the cam if they install the bearings.The oil holes are the same.Some line up great some not so good.Rocky
i didn't bring him the cam initially. i should have brought it, he should have asked 
but he took care of me...
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Re: cam bearings too tight
[Re: mickm]
#1083881
09/27/11 08:58 PM
09/27/11 08:58 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
got the block back from the machine shop, and the cam wouldn't go in. took it back, and we started playing with it. out of the block, bearings fit nicely on the cam. in the block, 3 out of the 5 were too tight. we did a lot of playing around, but finally i had to leave.
this is a mopar hemi (not world) mega block.
in the end, he found that all the holes were .0005 to .001 too small, and so were crushing the bearings when they were inserted in the block.
i brought him an old cam, and he grooved the journals on the lathe, and then inserted the cam and made 1 turn and removed it. buffed the bearings with scotchbrite, and now the cam fits like a dream!
how common is this on these blocks? i've heard of issues with these before, but all of the holes to be too small?
also the hole to the driver side head from the #4 bearing did not match perfectly, so i had him enlarge the hole in the bearing so it is completely open.
anything else i should be aware of here??
Thats quite common to have to size the bearings...
I have a cam for that purpose laying around here
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Re: cam bearings too tight
[Re: MR_P_BODY]
#1083882
09/27/11 09:00 PM
09/27/11 09:00 PM
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Joined: Jul 2006
Posts: 4,179
California
mickm
OP
master
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OP
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Joined: Jul 2006
Posts: 4,179
California
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Quote:
Thats quite common to have to size the bearings...
I have a cam for that purpose laying around here
well at least i have one now too! 
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Re: cam bearings too tight
[Re: mickm]
#1083883
09/27/11 09:34 PM
09/27/11 09:34 PM
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Joined: Dec 2006
Posts: 3,396
Pa
Hot 340
master
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master
Joined: Dec 2006
Posts: 3,396
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Quote:
Quote:
Thats quite common to have to size the bearings...
I have a cam for that purpose laying around here
well at least i have one now too!
Can you post a pic of the cam? Im trying to see what you did incase I run into this...
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Re: cam bearings too tight
[Re: Hot 340]
#1083884
09/27/11 11:34 PM
09/27/11 11:34 PM
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Joined: Jan 2003
Posts: 27,421
Balt. Md
383man
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 27,421
Balt. Md
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Had a problem with my 440 block when I built my 493. I put the # 1 and 5 cam bearings in and the cam turned fine so I installed the bearings one at a time. I found # 3 bearing had a scratch mark on the back of it as it had a small piece of metal rolled into the cam bearing bore making the bearing high at that spot. I looked where the bearing scratch was and found the protruding metal and removed it. Fixed it right up. Ron
Last edited by 383man; 09/27/11 11:34 PM.
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Re: cam bearings too tight
[Re: Hot 340]
#1083886
09/27/11 11:47 PM
09/27/11 11:47 PM
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Joined: Jul 2006
Posts: 4,179
California
mickm
OP
master
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Posts: 4,179
California
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Quote:
Can you post a pic of the cam? Im trying to see what you did incase I run into this...
i will get the block and cams back in the next day or so. i'll post some pics when i get my hands on it.
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Re: cam bearings too tight
[Re: Crizila]
#1083890
09/28/11 09:36 PM
09/28/11 09:36 PM
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Joined: Dec 2006
Posts: 3,396
Pa
Hot 340
master
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master
Joined: Dec 2006
Posts: 3,396
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Quote:
Quote:
Quote:
Quote:
Thats quite common to have to size the bearings...
I have a cam for that purpose laying around here
well at least i have one now too!
Can you post a pic of the cam? Im trying to see what you did incase I run into this...
One I just did for a sm blk. Cut the grooves in each journal on an angle and slanted towards the leading edge ( as you would rotate the cam bolt - clockwise ). Chamfered the trailing edge of each groove and stoned the leading ( cutting )edge.
I get it now. How much stock on the bearing can you safely take out?
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Re: cam bearings too tight
[Re: gbolten480]
#1083893
09/29/11 04:44 PM
09/29/11 04:44 PM
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Joined: Jan 2003
Posts: 25,881
Rio Linda, CA
John_Kunkel
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,881
Rio Linda, CA
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OK, the bearing bores in the block are undersized from the factory so that begs the question "what did the factory do?" The answer is they either scraped them or bored them.
I don't like the idea of using any abrasive material like Scotchbrite, sandpaper, hone, etc. due to the possibility of impregnating the soft babbit with grit.
The INTERNET, the MISinformation superhighway
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Re: cam bearings too tight
[Re: John_Kunkel]
#1083894
09/29/11 05:27 PM
09/29/11 05:27 PM
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Joined: Jul 2006
Posts: 4,179
California
mickm
OP
master
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OP
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Joined: Jul 2006
Posts: 4,179
California
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Quote:
OK, the bearing bores in the block are undersized from the factory so that begs the question "what did the factory do?" The answer is they either scraped them or bored them.
that also begs more modern questions. like if this is a known issue, why can't the factory just get it right on these newer blocks? it is obviously a simple machine setting issue, because the bores are not too big, or all over the place, they are always too small, and almost always by the same amount.
Quote:
I don't like the idea of using any abrasive material like Scotchbrite, sandpaper, hone, etc. due to the possibility of impregnating the soft babbit with grit.
makes sense. i would think that just going over them lightly as a final cleanup wouldn't do any harm though. one would hope...
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