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Cam bearing problem
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johnfin
Posted 2008-01-08 9:29 AM (#110063)
Subject: Cam bearing problem


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I installed new cam bearings on my 57' 301 and I have found that the tolerances are .001 to zero. In other words its too tight. I dont believe the 301 cam bearings need to be bored. Any ideas? I have been thinking of having a machinist polish down the journals .001 but I still feel that is the wrong way of doing things.
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Shep
Posted 2008-01-08 2:47 PM (#110091 - in reply to #110063)
Subject: Re: Cam bearing problem



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This could be caused by the cam bearings not being properly lined up in the cam bores, you may have to pull them and start over with another set, I assume you used the proper installation tool.
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johnfin
Posted 2008-01-08 3:51 PM (#110096 - in reply to #110091)
Subject: Re: Cam bearing problem


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I cant even get one journal in so its not an alignment problem. I measured the bearing bores and they are .001 to zero. The bearings went too small.
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57chizler
Posted 2008-01-08 4:11 PM (#110097 - in reply to #110063)
Subject: RE: Cam bearing problem



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That's why they make bearing scrapers.

If you have an old junk cam you can make diagonal hacksaw slits on all of the bearing journals and use it as a makeshift bearing reamer. As the cam is turned it will make the high spots in the bearings visible and a bearing scraper can be used to scrape the high spots.
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johnfin
Posted 2008-01-08 8:53 PM (#110143 - in reply to #110097)
Subject: RE: Cam bearing problem


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I have heard about a bearing scraper but never have seen one. The cam journals on my used cam could stand to be polished, would it be stupid to have a machinst turn/polish the journals down .001 for a better fit?
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dukeboy
Posted 2008-01-08 10:37 PM (#110159 - in reply to #110143)
Subject: RE: Cam bearing problem



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I've run into this on a 440...Put new cam bearing's in, the cam won't go in the motor...
Machinist went through about three sets of bearing's before we finally figured out that it was a core shift problem...

Did you have the block hot tanked? If not, then a fine film of oil varnish may have been inside the bores, causing the bearing's to become too tight when installed..
If tanked, then the only way to get them to fit properly, would be to "Size" the bearing'
s like was posted, by either reeming, or "honing" the cam bearing's to proper size.........
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big m
Posted 2008-01-09 2:15 PM (#110206 - in reply to #110063)
Subject: Re: Cam bearing problem



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Is the inside diameter of the bearings correct?

One fellow I know assembles engines for a living, and when he has this same problem, I have seen him set the bearing in dry ice for a few minutes, and when centering the installation tool, the problem bearings went in fairly easily.

I had always either scraped or honed the bearings, if fit problems were discovered inside or outer surfaces, but this 'dry ice procedure' always worked well for my friend. ---John
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johnfin
Posted 2008-01-09 4:35 PM (#110226 - in reply to #110206)
Subject: Re: Cam bearing problem


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The bearing id, after pressed in, is a hair too small. Most cam bearings I have installed go right in and the cam slides in without a problem.
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big m
Posted 2008-01-09 7:36 PM (#110242 - in reply to #110063)
Subject: Re: Cam bearing problem



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If you don't have a bearing scraper, use '57 Chizler's advice on using an old cam to accomplish this. ---John
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johnfin
Posted 2008-01-20 12:04 AM (#111555 - in reply to #110242)
Subject: Re: Cam bearing problem


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Cam is installed but I need a ratchet wrench to turn the cam over. Is this common with new bearings and will it break in ok being tight.
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JERSEYBOB
Posted 2008-01-20 11:10 AM (#111610 - in reply to #111555)
Subject: Re: Cam bearing problem



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No way !! Too tight, your gonna wipe it out if you fire it. I would start doing some carefull measurements and find the problem first before you close this engine up. Where did you source the bearings from ? Is it a new cam ? Are all the bearings too tight?
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johnfin
Posted 2008-01-20 8:04 PM (#111649 - in reply to #111610)
Subject: Re: Cam bearing problem


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They are brand new clevite bearings, cleaned the bores and checked the dimensions yet when press in the tolerances get real tight. All bearings seem tight without high spots. Just a very tight fit. When you think about it, spec is .001, thats .0005 a side. Thats a super tight tolerance to begin with.
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DeSotohead
Posted 2008-01-21 7:59 AM (#111691 - in reply to #111649)
Subject: Re: Cam bearing problem



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The cam, when oiled and installed should be able to be rotated by hand using the timing gear placed on the front.
If yours does NOT do this, then your cam bores most likely have moved and are not concentric with each other.
Pull the cam, look at the cam bearing bores and where you see rub marks, and then carefully using an X-acto blde scrape the surface of the bearing around the rub area and across it. Don't take off too much, and do this for each bearing where the witness mark(s) appear.
Wipe clean, reoil, reinsert and try the turn method again.

You may have to repeat this several times, but the goal is to get the cam to turn freely in its bores. It doesn't have to be loose, but it should not "cog" as it turns.

I would expect that you have at least three bores that are SLIGHTLY non-concentric, and this will align them.
You will not remove much metal off the cam bearings to do this.

I have done this in the past (215 Aluminum Buick block - local machine shop said THEY COULDN'T FIX IT), and it is still running 20 years later.......
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Powerflite
Posted 2020-05-02 9:16 PM (#597670 - in reply to #111555)
Subject: Re: Cam bearing problem



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Great advice here. Does anyone know if a cam bearing install tool for a small block LA motor would work well for an early hemi motor? I'm trying to avoid using a universal tool, as I hear they are junk.

Edited by Powerflite 2020-05-02 9:17 PM
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BigBlockMopar
Posted 2020-05-04 5:44 AM (#597739 - in reply to #110063)
Subject: Re: Cam bearing problem



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Nothing wrong with (quality) universal cambearing tools. It's the operator that causes good or bad results.

johnfin,
Since you've already tried to rotate the cam, take it out and look at the bearings for where they were tight.
Scrape the bearing in those spots with a knifeblade. The material is soft so it scrapes easily, and any imperfections from that are quickly flattened again by the cam once in operation.

On bigblock engines it is 'normal' that new cambearings are too tight. It's a common thing.
As mentioned, an old camshaft with diagional slits cut in the journal is a perfect reamer for this. Done it myself a couple of times.

Your 301 needs the same work done. Either scrape the bearings or use the old cam to ream the bearings.
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Powerflite
Posted 2020-05-15 11:42 AM (#598317 - in reply to #110063)
Subject: Re: Cam bearing problem



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Update: Based on the dies on the installation tool that I have, the small & big block motors have 5 differently sized bearings with the largest at the front and progressively getting smaller, but all the bearings on the Chrysler hemi are the same size except the last one. And that last one is smaller on the hemi than the same one on the small block. It is also the only one that is different on the big block as well. The other 4 bearing sizes on the big block are the same as the small block and the largest #1 bearing on the small block is the same size as the front 4 bearings on the early hemi.

So the tool I bought doesn't have the correct size to install the rear-most bearing. To install it, I used an old 331 hemi cam and installed the old bearing onto it after filing the edge of it flat to ensure it wouldn't wedge on the new bearing. Then I re-nstalled the old front bearing (with part of it hanging out of the front of the block) and intalled the cam into the motor with the new bearing at the end of it, butted up against the old bearing. Then I hammered the cam to install the new bearing at the back of the motor. Take it back out, along with the old front bearing and install the other bearings with the #1 die from the small block kit. Worked out pretty well. I did end up cutting the old bearing to reduce it's width (not shown in the picture). I did this to provide more contact surface inside the new bearing, and leave just enough of the old bearing to still keep it centered on the cam journal.

Edited by Powerflite 2020-05-15 9:27 PM




(Rear Cam Bearing Install Tool.jpg)



Attachments
----------------
Attachments Rear Cam Bearing Install Tool.jpg (223KB - 80 downloads)
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57chizler
Posted 2020-05-15 1:20 PM (#598319 - in reply to #597739)
Subject: Re: Cam bearing problem



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BigBlockMopar - 2020-05-04 2:44 AM

Nothing wrong with (quality) universal cambearing tools. It's the operator that causes good or bad results.


Bingo !!
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Powerflite
Posted 2020-05-15 2:14 PM (#598324 - in reply to #110063)
Subject: Re: Cam bearing problem



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The key word there is "quality". It is my understanding from the reviews I have read, that they are now all made by the same manufacturer in China and the "quality" word no longer applies to them. But since the 392 really only needs 2 die sizes, it would be pretty easy to make up your own tool for both of them using an old cam.
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samstrader
Posted 2020-05-15 6:35 PM (#598336 - in reply to #110063)
Subject: Re: Cam bearing problem


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This was a pretty cool idea Powerflite. Now you are an official professional cam bearing installer. I bet they are installed perfect..... Really good idea.

"""""So the tool I bought doesn't have the correct size to install the rear-most bearing. To install it, I used an old 331 hemi cam and installed the old bearing onto it after filing the edge of it flat to ensure it wouldn't wedge on the new bearing. Then I re-nstalled the old front bearing and intalled the cam into the motor with the new bearing at the end of it, butted up against the old bearing. Then I hammered the cam to install the new bearing at the back of the motor. Take it back out, along with the old front bearing and install the other bearings with the #1 die from the small block kit. Worked out pretty well.""""""
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Powerflite
Posted 2020-05-15 9:29 PM (#598341 - in reply to #110063)
Subject: Re: Cam bearing problem



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Thanks Sam. I added a couple of details in the procedure that I left out originally.
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