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New cam doesn't fit the block, what is the best fix?

Posted By ogasman Last Month
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ogasman
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I have a 56 292 that I am building.  Had the block tanked, bored, new cam bearings.  Went to put the new Isky cam in, no bueno.  It fit the first 4 cam bearing a little snug.  When it started into the 5th it bound up hard.  The cam looked good when I cut the oil groove deeper, but I did not put a mic on it.
  I still have the old cam.  It had quite a few miles on it, and a couple flat lobes.  I can get it into all 5 bearings, but it is a lot tighter than I would run it... Cannot turn it over by hand.  I have seen where people cut a cross grove into the old cams bearing journals, and use it as a reamer to open up the new bearings.  Is this a good idea?  Anyone know something better to do?

Paul
Cliff
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Run a little scotch bright around all the bearings (softy) sometimes 2000 grit sand paper is necessary, be careful when the cam fits clean the crap out of it, this is normal work most machine will do this and not tell you what they did. 
blocky
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yes good old scotchbrite.make sure the cam spins
blocky
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yes good old scotchbrite.make sure the cam spins
Florida_Phil
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I had this problem a number of years ago on a 312 build.  I never had it with FEs or small blocks.    I understand it's a common problem.  I had to scrape the bearings to get the cam to turn freely.  I took me some time, but I finally got it done.  It made me somewhat nervous as it seemed like a Neanderthal fix.  Looking back, I probably should have taken the block back to the machinist.   Must have been OK as I ran the engine for years without a problem.


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darrell
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ive installed cams with slight drag after putting in new bearings and didnt have a problem.as long as i can turn it by hand.
Joe-JDC
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Supercharged

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I would try the old camshaft and see if it will slide in.  If it will, then measure the journals on the new one and compare.  May need to remove and replace that last bearing.  Joe-JDC

JDC
ogasman
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I think I fixed it.

The old cam would slide in, but it had a little drag on all the bearings as I spun it when I put it in.  It seemed like the 4th and 5th bearings were the worse.  It was pretty hard to turn when all the way in.  Could not turn it by hand.  The new cam would make it to the 4th bearing with a good amount of drag.  It would not go into the last bearing.  I thought about fitting it by hand, but I could see more than one shiny/high spots a few places on different bearings.  I put two narrow (less the 1/16 inch) angled grooves on opposite sides of each journal of the old cam,.  Put some grease in the grooves, and put it back in the motor.  I slid it straight into the motor, and then started to turn it over when it was all the way in.  I could feel it start to get easier as I spun it.  I worked it in and out a little bit once it turned over easily.  I got out a decent amount of material from each bearing journal, more on the 4th and 5th bearings.  I tried the new cam, now it fits.  It still has a bit more drag that I would like, but it will probably be alright.  The finish on the bearings was not perfect, but not too bad.  

Paul
Richard
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Check to see if the cam is slightly bent. This happens more then you think. A good machinist can Chuck it up in his lath and check with an indicator  and can straighten it for you.  
55blacktie
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Cam-bore alignment could be the problem. 


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