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Discussion Starter · #1 ·
Ok it is a 75 CJ5 304 and this problem is driving me nuts. First the dist gear was eaten up. Now this was from the cam walking. I have it all striped down and I put another cam in with different lifters and new timeing chain, and it is still walking. What could be the problem of this? Bearings or is it the lifters.
Oh yea when I take all the rockers off so there is no pressure on the cam, the cam doesnt walk. but when I put one or two back on it walks.
I have been trying to figure this out and I am kinda stumped right now.

Thanks

 

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/wwwthreads_images/icons/frown.gif This is a HUGE problem with the 304s, and nobody seems to have the answer. Of course there is nothing to KEEP the cam from walking to begin with except your good looks. Why not call American Performance in FLA....407-632-8299...and describe the problem. If anyone knows why it should be them. I have a theory....but it is only that.....My theory is that the cam HYDRAULICS out of the last bearing....you know the one...it has a soft plug behind it...when the oil seeps by the cam bearing and into that cavity, it builds pressure and the cam is pushed out. I don't know if the two-year-old who designed the AMC V8 oiling system put a relief hole or not to relieve the pressure, but American Performance would surely know./wwwthreads_images/icons/crazy.gif

CJDave
 

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i think bearings is the culprit

chilton's manual says...

0 endplay allowed

good luck/wwwthreads_images/icons/smile.gif

jimbo

'74 CJ5,232 I6,T15,Dana 30&44
 

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Don't some high performance engines use a Teflon button on the inside of the timing cover to prevent
this problem?

 

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Discussion Starter · #5 ·
CJDave

Well here is the thing. There is NO oil pressure when I turn the motor over. I have it torn down to just heads, block, crank, and cam.
THERE IS NO OIL PRESSURE AT ALL (NO OIL), it does not run, I am just cranking the engine over and it is still walking.



 

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/wwwthreads_images/icons/tongue.gif In that case, I would have to go along with the bearing theory. If both cam and lifters are different, what else is IN the system except the cam bearings that could make it do that. Oh, another possibility....check the crankshaft end play....make sure it isn't pulling the cam out. The newer the chain, the worse it would be. Just a thought./wwwthreads_images/icons/crazy.gif

CJDave
 

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You said you changed the timing chain, but did you change the timing gear/sprocket on the cam? Just
a little warp from using a screwdriver to pull out the cam could cause this. Maybe? Just another
thought. I know you're frustrated.


 

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Discussion Starter · #8 ·
Well the other thing is...if i pull all the push rods out (and spark plugs)
with no pressure on the cam. It will not walk....SO I think it would be the lifter......I am not sure though, trying to get some opinions on that part of it.




 

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/wwwthreads_images/icons/tongue.gif But the lifters and cam are not the same ones, so whatever is causing it is independent of the lifters or cam. The alignment of the chain drive IS critical, maybe take a good look at that, AND check the crank end play. /wwwthreads_images/icons/crazy.gif

CJDave
 
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How do you measure end play when this engine does not have any physical means (some kind of stop) to hold the cam in other than the timing chain,the taper ground into the cam and distributor drive.I assume that you have removed the distributor and you said you removed the lifters ,so that only leaves the timing chain. so you will have walk under this condition.Did you check to see if you have the fuel pump eccentric,distributor drive gear and retaining bolt and washer on properly and torqued to 30 FT LBS ?
you said that there was no oil pressure and you knocked out a distributor gear .
you sure that the problem is in the cam and not in the oil pump ?
the following statment is taken out of the Mopar Jeep engines book.

Camshaft end play is maintained by the load placed on the camshaft by the oil pump and distributor drive gear. The helical cut or the gear holds the camshaft sprocket thrust face against the blockface. Camshaft end play is zero during engine operation the rear camshaft bearing journal has two holes drilled through it to relieve pressure that could develop between the journal and camshaft plug and force it forward

JF1 text
 

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/wwwthreads_images/icons/tongue.gif That is a very critical piece of information JF1. So there IS an oil relief to keep from pushing the cam out of the bearing box at the rear. AND...it appears that the distributor drive is critical to cam end play.....as in the bushings need to be stellar in both the oil pump and the distributor. That might be a good place to start looking.....at the distributor shaft bushings. We think the cam walks and destroys the distributor drive gear, biut it is actually the distributor which deflects and does it? Hmmmm...? /wwwthreads_images/icons/crazy.gif

CJDave
 

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Discussion Starter · #12 ·
But if the Dist gear and oil pump hold it in place. Why did it shread the Dist gear then? Something other that the Dist and oil pump "pushed" the cam out to eat the gear? It is a new timing chain and gears. And NEW Dist (whole thing).


 
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when you install the distributor there is a tang in the bottom of the shaft that interlocks with the pump and is a solid connection,with all the valve train installed there is a tremendous amount of pressure on the cam!and the gear on the cam is being turned by the crankshaft thru the timing gear.
Are you sure the oil pump is turning and not jammed?
this is simple to confirm ,remove the distrubitor and use a long screw driver and place into the oil pump drive slot,you should be able to turn this by hand!
also look for an alignment problem with the distributor.

JF1
 
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I can't see that even if the cam is walking that it would knock out the gears,still sounds like something binding somewere.
is the timing gear on with the thrust surface to the block?
fuel pump eccentric on with the side that is stamped (back) towards the block?
distributor drive gear on cam with the recess for the washer toward the front?
Is the gear on the distributor on correctly?
If you remove the distributor does it turn freely?

JF1
 
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just a simple question,when its all in as it should be before you turn it any,is the crank and cam gear teeth in same vertical plane?neither
in or out farther than the other when viewed from the side? And i wonder if distrubtor and oil pump keeps it from walking,or is sposed
to,how can it move to far forward with those installed by just turning it over if everything isof the correct parts?


 
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Even if a lifter was tight it still should have nothing to do with the distributor gear,the cam is being driven by the crankshaft by the timing chain and if there was a problem with the valve train it probably would not turn at all or would cause damage to the chain.
The distributor gear it self does not hold the cam in,it does when the engine is running,the oil pump is turned by the camshaft gear thru the distributor,which creates a load by pumping the oil,this load forces the cam into the block due to how the gears are cut.
something has to be severly out of line or binding.
if the cam was walking you would see some nasty marks in the back of the timing cover.(i have yet to see a cover that does not have some minor marks)
are you using the dowl pins that go into the front of the block to maintain the timing covers postion?

JF1
 

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jeepfreak1 ......bring the mentally challenged (me) up to speed here........(if I grabbed what Dave was getting at) if the CRANK had excessive end play ......and nothing holds the cam in except the chain .......and the crank was "forward" .......wouldn't the cam want to track out by the action of the chain trying to align? That is, wouldn't, in this "open" scenereo anyway, any crank end play .......also be cam end play (so to speak)? ...........so if one measured the crank end play ..............why don't you think that the cams free travel would match it?
Just curious......
GeeAea

 

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jeepfreak1

I could be real screwed up here, it's been a while since I looked down some lifter bores, but... I was
thinking that the lifter bores did not line up with the cam lobes in order to to turn the lifter slightly each
time the lobe comes up. If the bore is loose, could the lifter cock enough to push the cam forward? If
the bore is tight, would the lobe want to follow the curvature of the lifter? I'm just a shadetree mechanic
and I may be grasping at straws here! To recap the problem as I think I understand it, lifters in - cam
walks, lifters out - cam doesn't walk. Two cams and two sets of lifters exhibited the same problem.


 
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