curious cam sprocket wear- 340

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Neal Zimmerman said:
I agree with rusty, if the cam key was cocked up in the back that could explain the cam gear being "forward" and shoving the eccentric into timing case, but it doesnt explain how the front of the thrust plate and cam sprocket did their bump and grind as seen in photos.
neal
Click to expand...
I can very easily see the cam moving back and forth, and when it moved back, it could hit the thrust plate with some vigor. The forward pressure of the oil pump resistance and the lifters on the lobes is fighting the chain tension as it tends to keep the sprockets aligned evenly, and the cam is going to move back and forth as long as there is any slop in the clearance.

I would reassemble with the intermediate shaft out as suggested and check all the end plays.
 
SST3193, I think u nailed it, yes indeed those two lowest water pump bolts appear to be in perfect alignment with"machined" groove of cam sprocket, and yes indeed those bolts were too long ( not my doing, last owner). I am going to reassemble everything and with a blob of red paint on end of long suspicious bolts try to verify. Still doesn't really explain scrubbing of inside of timing case, unless we have an example here of what doctors call ' co-morbidity", or multiple factors athe same time. Wondering if timing set was actually for a 318/360 MAGNUM.
Will report my findings.
neal
 
yep, that was it. reassembled the whole thing and put blobs of red paint on ends of offending bolts and threaded them in-the picture tells the rest. As for the scrubbing inside timing cover, I believe that might have been from another time, someone not seating fuel pump eccentric down over cam key. I opened a small block once before where someone had down just that and it had identical marks. in theory the fuel pump could still work, even though eccentric would be doing a crazy orbiting wobble. I measured clearance of fuel pump eccentric to timing caase and there's an easy 1/8 inch so i believe that was from another time. I am going to yank intermediate shaft and check out drive teeth. Could be knife edged from zero endplay on cam. If so I will replace cam, lifters and intermediate shaft . Gonna cut open oil filter and examine it for sparklies, but this probably happened a long time ago, Maybe a new oil pump. Maybe a new engine, I don't know. It had good oil pressure a few weeks ago when i had it running and like i said this probably happened several years before i got car.

P1010046 (640x479).jpg
 
Pretty amazing... a danged good call by SST3139!

Since the pan will be off to check the oil pump, maybe pull a coupla of main and rod bearing caps to see how much if anything got through the filter.
 
were the 2 pump bolts hitting the chain? and U know the cam thrust plate bolt with the hole belongs at upper hole
 
no, the 2 pump bolts were hitting right where the red dots are in the picture. didnt hit chain, just rode right there on sprocket. yep i know about the bolt with the hole.
neal
 
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