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Wow, that was a long string to read through. I remembered the oil pump is moving freely. I remembered there is no oil pressure. OK, I think the problem is with the oil pump. With oil in the oil pan and assuming the oil pump gears are turning???????, you will get some oil pressure, maybe just a couple pounds of pressure. When the oil pump gears turn you will get some oil flowing. The AMC oil pump system will send oil to the crankshaft first. So even if there were no cam bearings in the engine block at all, there would be some oil pressure created by the tight bearing clearances of the crankshaft.
If it were my engine, I'd pull the oil pan and check the oil pump. It could be that the gears of the oil pump jammed, causing the distributor gear to be chewed up because the oil pump shaft stopped turning. Then maybe the oil pump shaft broke. It's not impossible. Just my 2 cents worth.

dave

 

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/wwwthreads_images/icons/tongue.gif The gears suffer because the centerlines of the two shafts no longer perfectly intersect, , and there is very little tooth engagement remaining, so the load from the oil pump becomes more than the very tips of the gear teeth can handle and it tears away the metal./wwwthreads_images/icons/frown.gif

CJDave
 

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/wwwthreads_images/icons/tongue.gif All the good engines have the lifter bores offset to the cam lobe to cause rotation except.......SMALL BLOCK CHEVYs! Yep....they don't have enough offset. SO......you NEVER let a SB Chevy idle......the lifters are scuffing the cam. Thankfully, the AMCs are offset enough to cause rotation./wwwthreads_images/icons/tongue.gif

CJDave
 

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/wwwthreads_images/icons/crazy.gif I've learned not to underestimate the end play on crankshafts...ESPECIALLY with real heavy manual clutches, it's easy to wear out the thrust surface and have the crank walking back and forth in the mains. That could easily overcome the feeble gear pressure that is used to hold the cam in place. CHECK THE CRANK./wwwthreads_images/icons/crazy.gif

CJDave
 
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Just a couple of thoughts. I had a problem with my oil pump and cam about a year ago when building up a 258. I went through several oil pumps and two cams. I called and talked with engineers at Comp Cams and a few others. The third time, I put all of their advice together and did not have the problem. (1) I discovered that a performance product was made to replace stock - that being a spring loaded bolt that installs in the back of the timing cover and puts a constant pressure on the camshaft. (2) that the cam and oil gears need to be carefully deburred, (3) that adequate lubrication needs to be put on the oil gears to allow them to actually seat with the cam, (4) adequate lubrication on the lifter to permit it to "seat" with the cam, (4) got rid of high volume oil pump that puts more pressure on cam. Only to add to the discussion. Thanks, Mindbender

Mindbender
CJ7 258
 

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Discussion Starter · #27 ·
Thanks for all the info. I am going to check the endplay in the crank first. Then if there still exitst a problem i will try a new set of lifter. ( so i know they are perferct) and see what happens. I will keep you posted on what happens!

 
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As I understand it, all modern lifters (cam followers) are convex. They are not flat. Further more the cam lobe profiles are not parallel with the long axis of the cam. They are gound at a slight angle. The results of these two items of interest is that the contact point of the lobe/follower is offcenter. Which means that the follower always rotates. Keeps them from wearing out so fast. Designed that way. Which brings us back to the original question: why's my cam walk? If all of the lobe faces were ground on the same bias (all slants toward the same end) then the cam would HAVE to walk toward that other end. I assume that the cam is walking forward and not rearward. I also assume the cam sprocket has a thrust face keeping it from walking rearward. If it is going forward, then the timing chain/crankgear is going to exert some influence to keeping the cam in place. I think that this influence would be less than the influence of the distributor gear. If I am correct about the bias cuts being all the same direction, then I would think there is no way the distributor gear could hope to compete with the valve spring pressure on all of those lobes.
The first major problem I have with my own theory is that I can't see a cam manufacturer making this mistake. This isn't new stuff to them. But everybody makes mistakes and it could be a simple as the CNC setup man duplicating his first set of cam profiles to the other fifteen. Second problem I have is that the timing chain cover should have some serious marks. Especially since the distributor gear has gone south at least once.

Just a thought: the cam sprocket/timing chain/crankgear assembly should adhere to the axiom that the shortest distance between two points is a straight line; if the cam is walking the chain is in a curve. And it won't want to be there.

Keep us all posted.
sln

 

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My buddy had a similar problem and the cam he got was a marine grind and it did just as yours is doing . The company that srewed up the order said marine grinds are angled because the engine sits at such an angle in the boat so the grind compensates for this . Probably not your problem but hey , all info. is helpful .
Good to see you back CJDave !!

Jeff



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i would contact comp cams help line and ask if they would have a cam button for your cj5 they might be able to help solve your problem, the buttons are usually used for roller cams.

1-800-999-0853 comp cams help line number

 
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