RE-Rebuild of AMC 304, Part II

[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]

http://www.geocities.com/wpww_tkc/photos.html

[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.........

[fuzz401]

Hmmm think I have said that the whole time :-|

[Pheonix]

Yes you did, but the other guy put it in terms that i could understand. You were right, thanks for the help Fuzz401, Jeepsr4ever, Lifted79CJ7, Barry Kaul, and W.T.Sumner for all your imput and help. My block is in the shop getting re-honed and my crank getting ground down .010. then a new cam and front timing cover should get it going down the road again.

[Barry Kaul]

Good luck man.

[jeepsr4ever]

Elliot is a member here as well and a AMC fan

[Pheonix]

http://www.geocities.com/wpww_tkc/photos

I called the place where i bought the cam kit and they said that their cams were new, not reground and that this is the first time they have ever had a problem. So i started looking at the timing sprocket again and did some comparing to the old one. I noticed that the keyways lined up but the Oil groove was off. I then put them on the cam the way you would assemble them, put the cam verticle on the table and slid the cam out so i could see how they lined up, they didn't. Also there is a considerable amount of casting flash on the sprocket oil groove itself. I then put some chalk on the oil hole of the cam and slid on the sprocket, the oil hole was off a couple of degrees with the little oil hole on the sprocket only about 1/4 of it was open. I will call the manufacture on monday to see what they have to say about this.....

[jeepsr4ever]

pretty common.......shouldnt be though...try dremeling out the flash and drilling the hole oversize...the material is soft

[Pheonix]

this one is junk, i am upgrading to a cloyes roller timing chain & sprockets, well or i hope it is an upgrade......

[Lifted79CJ7]

I haven't really looked at mine, but you guys ever hear of that problem from Edelbrock double rollers?

[jeepsr4ever]

not yet :-|

[craigparrish]

i'm rebuilding a 304 and this cam walk stuff has me worried. i happened across this anti walk kit on ebay. is it worthless or a good insurance policy?
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=33614&item=2475015701&rd=1&ssPageName=WDVW

[jeepsr4ever]

If your cam is walking it is either a roller cam or has completely worn out lifters...You dont need a anti walk kit with hydralic cams

[craigparrish]

i'm using the edlebrock performer cam which is hydralic so i'm safe then. thanks, you saved me a couple hundred bucks as i was about to get the kit.

[JERSEY JOE]

Craig: are you in OHIO?

[craigparrish]

Yep, you must be the same Jersey Joe that got my old tub. I hope it worked out well for you, you seemed like a really nice guy. Wife liked the "Jersey Joe" license plate to.

[JERSEY JOE]

Yes it's me!!! Actually I am just finishing the chassis. I could send pics to your email ad if you want them. the tub is being worked on slowly. It will be finished by the end of May.