Pheonix
I rebuilt my 304 all back to Manufacture specs. Thinking that it should at least last another 85,000 miles with no problems powering my Jeep CJ-7 around. Unfortunatly it only made it 400 miles before i noticed in the oil change that there were a good amount of metal filings. I pulled the distributor thinking i could see the timing gear chain and sprocket to see if that was what was going out, I noticed that the timing gear on the cam for the distributor was almost wore smooth. I pulled the timing cover and replaced the gear, and all the gaskets, thinking that i had just bought a bad gear. But now, at mile 750 it has wore out totally now, again. This time i now have the entire engine pulled out to go throught it again. This is really frustrating as i had thought i had the problem fixed and i have been working on this jeep for 4 years now and have never had a summer to enjoy driving it around. I just got back from Iraq thinking that i could cruze around in my jeep, instead i am stuck in the shop again, spending another summer tearing down my engine. I need help finding out the problem. thanks
Barry Kaul
That sounds alot like the problem other people have had with defective timing chain sets. There are some posts about that issue here somewhere. That sucks though, I feel your pain.
Pheonix
jeepsr4ever
The pics didnt show up and the links dont work........ :-|
Pheonix
Geocities suck,
i have no other way of getting the photos on here!!!
fuzz401
http://photobucket.com/
could be the cam lobes causing the cam to walk around too
Pheonix
What would cause the cam to walk? it is a new stock cam with new bearings. Why would it cause such premature engine failure? If you want to see the pics of the parts i fixed the link above.
W.T.Sumner
I had one do the same thing several years ago. After 3 sets of distributer geers I changed the timing cover. Its been fine ever since.
Pheonix
The metal shavings also ruined all cam, main, and rod bearings. I now have to get a new cam, regrind crank, and new bearings, along with new timing cover and gaskets
http://geocities.com/wpww_tkc/photos.html
Lifted79CJ7
That stinks phoenix. So why not take this time and move up to a 360? Just a thought (I am a bad instigator!). Anywho, check out under the oiling page and see what you can dig up. Sounds like a bad cover to me as well. Talk to MC and see what he recommends. http://www.bulltear.com/forum/viewforum.php?f=25
Jack
Pheonix
Maybe i'll just go with a 401, or maybe a Ford 302 or Chevy 350? I would have love to stay with the 304 but this has just set me back at least another $800. and i don't know if i want to risk that much again on something i cant solve........
Pheonix
Everyone claimes its the cover... how can the cover cause this problem when it worked before? The cover was the original and it was in good shape and carried good oil pressure.
Lifted79CJ7
My first Jeep I bought, had the 304 rebuilt and the engine died due to the original cover within a day. Just consider it one of those wear pieces. Oil pressure might not have anything to do with it, but if the cam shaft gears are not lining up with the distributor gears correctly (new oil pump gears, etc), then they will wear fast - kind of like not setting up a ring and pinion correctly. At least thats what I get out of the whole topic. MC or Fuzz, you wanna pipe in here?
Jack
jeepsr4ever
did you remember to install the alignment pins in the block for the timing cover?
Pheonix
Yes, both pins were in.
What is supposed to hold the cam from going too far into the block? I checked on mine and the Timing Sprocket rubs on the block..... This can't be right. There has to be something set up so it doesn't wear into the block, it is already showing some signs of wear...
fuzz401
some time back there was a bad batch of cam shift billets and the lobes were not in the right spot with them being off a little it caused the lifters to push the cam forward on the top of the lobe at the base it would walk back
and I beleave there is only 1 or 2 people that make the billets for all cam makers
Lifted79CJ7
There is a freeze plug looking little guy in the back of the block that should be set to keep the cam shaft from travelling. Check that.
Jack
Pheonix
How do you know if the freeze plug is right? the cam goes back 1/8" too far into the block past the bearings. The only thing keeping it in line with the bearings is the timing sprocket hitting the block.
jeepsr4ever
pheonix
Its the lifters that keep the cam from bottoming back there
Pheonix
Here is what Elliot from Froadin.com had to say.......
"I was just reading about cam walk in AMC motors and apparently the cam lobes on the stock AMC are designed with mmmm.... "slope" in them that actually keeps the cam from walking. That is something that some lame cam grinders do not incorporate. I think it was about every post I'd read, where there was walk and gear damage, that replacement of the cam solved the problem. Typically gear failure occured withing 1000 miles of rebuild or sooner.
Anti walk buttons can be obtained from Performance American Style, but those are really intended for use with roller cams.
If you find scoring on the inside of the timing cover or have endplay in the cam... you found the culprit. I think you are on the right track."
I think he is too, I have endplay in the cam and there are score marks on the inside of the timing cover. Also my engine failed at mile 750 and The cam came with a rebuild kit so it was likely a regrind. Thanks to Elliot at Froadin.com.........
