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the cam/distributor gear issue

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dane View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dane Quote  Post ReplyReply Direct Link To This Post Topic: the cam/distributor gear issue
    Posted: Feb/01/2013 at 2:18pm
After cranking and cranking I finally figured out why my 360 would not run. The cam gear was chewed up and not letting the distributor turn right. I am going to attempt to pull everything off the front of the engine and replace it. I'm going to buy the bulltear matched set that everyone seems to like. I know this seems to be a common problem with amc's. Has anyone else had these issues? Also please feel free to share the do and do nots you have experienced with this...
 
 
This happened to me one other time with this same engine, but that time it was the distributor gear. I had both gears replaced and an external oiler drilled into the timing cover, and now its happened again, maybe 3-4k miles later...Dead


Edited by dane - Feb/01/2013 at 2:18pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 72AMX Quote  Post ReplyReply Direct Link To This Post Posted: Feb/01/2013 at 2:24pm
You shouldn't have to use an external oiling source to lubricate the gears, I'd advise you to look over the various cam/distributor gear threads on this forum and look at some of the recommendations suggested in them to verify your gears are being properly lubricated before you install your new matched set of gears.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FuzzFace2 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/01/2013 at 3:01pm
Yes do as 72AMX said and search. Some of the gear issue is the way the chain cam gear is machined to let oil tru to the dist. gears but cant see that because of your oil line.
The other was bad timing covers did you buy a replacement?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dane Quote  Post ReplyReply Direct Link To This Post Posted: Feb/01/2013 at 3:40pm
Originally posted by FuzzFace2 FuzzFace2 wrote:

Yes do as 72AMX said and search. Some of the gear issue is the way the chain cam gear is machined to let oil tru to the dist. gears but cant see that because of your oil line.
The other was bad timing covers did you buy a replacement?
Dave ----
 
I have not ordered parts yet.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote pipefactory Quote  Post ReplyReply Direct Link To This Post Posted: Feb/01/2013 at 4:04pm
Hey guys my 1st post in a while.  not trying to go off topic here but, a friend and I are building a 390 stroked to 401 for a car that my interest everybody that knows about AMC's, group 19, 390 engines.  More of that later.
As to your problem, I've found as others have said about oil holes not lining up with cam journal oil hole, cam gear oil hole, all the way through to the distributor drive gear.  in the end when you make sure all passages and holes line up.  I like to look in through the hole where the fuel pump bolts on while spinning the oil pump with a drill.  You should see oil pumping out of 4 holes in the dist drive gear.  Also as to the engine we are building we found that the 2 piece fuel pump ecentric was giving us .010 runout on the dist drive gear.  something to look for.  By the way the car I'm talking about is the one a couple of AMC engineers were using as a test car for things like group 19 cams, cross rams and other speed parts.  But what is interesting is it's a 1967 Rebel that was running a 390 (in 1967), 4 speed and cross ram.  It'll be running the original cross ram that Vic Edelbrock made which we think was the 1st one built.


Edited by pipefactory - Feb/01/2013 at 4:07pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ccowx Quote  Post ReplyReply Direct Link To This Post Posted: Feb/01/2013 at 5:57pm
Cool car, Pipefactory! I am a big fan of the various Group 19 stuff and a prototype is neat! A 67 with a 390?! How much like a production engine is it?

As for the cam gear issues, I have fought this battle myself. As the gentlmen above say, oiling holes through the gear from the oil galleries need to be checked. It would not hurt to actually take a dremel tool or similar and make sure they are cleaned out front to back and watch for oil coming through. After that, check the timing cover and fuel pump eccentric. Since you did add the external line I would pay special attention to the timing cover.

If the timing cover lines up and the factory oiling holes are good, you should be fine. Factory motors ran 100,000+ miles without a hiccup so the engineering is sound. You should have no issues if all the factory systems are working as per spec, even with two mismatched used gears. Ideal of course is a new matched set but it should be fine regardless.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote amxess Quote  Post ReplyReply Direct Link To This Post Posted: Feb/01/2013 at 11:26pm
If you replaced the distributor gear with a new one bought from a Chrysler dealer or elswhere in last few years (I'm thinking last 12 or so), that is where most of the cam gear issues came from. These aftermarket distributor gears which even Chrysler sold, were not the same as the originals and ate up the stock cam gears (much harder metal than the cam gear and maybe mismatched also). We did a few AMC motors with these new distributor gears and all chewed up the cam gear-some within a couple of days to a few thousand miles. Went back to using old used original distributor gears and had no problem. Think after the problems became known, most stopped selling them and everyone was scrambling for old good originals. Bulltear then came out with a matched set of cam/distributor gears a few years ago and that's all I will use now and had no problem with theirs.
 
Also use the "Rollmaster" timing chain gear sets as they have no oiling issues to the cam gear.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote pipefactory Quote  Post ReplyReply Direct Link To This Post Posted: Feb/02/2013 at 6:18am
Originally posted by ccowx ccowx wrote:

Cool car, Pipefactory! I am a big fan of the various Group 19 stuff and a prototype is neat! A 67 with a 390?! How much like a production engine is it?

As for the cam gear issues, I have fought this battle myself. As the gentlmen above say, oiling holes through the gear from the oil galleries need to be checked. It would not hurt to actually take a dremel tool or similar and make sure they are cleaned out front to back and watch for oil coming through. After that, check the timing cover and fuel pump eccentric. Since you did add the external line I would pay special attention to the timing cover.

If the timing cover lines up and the factory oiling holes are good, you should be fine. Factory motors ran 100,000+ miles without a hiccup so the engineering is sound. You should have no issues if all the factory systems are working as per spec, even with two mismatched used gears. Ideal of course is a new matched set but it should be fine regardless.

Chris   
This spring I'm going down to his garage party and gonna start taking a lot of pics.  Think the 390 was a stroked 343.  I think he has that motor there.  Heres the car.
 
 
http://www.hemmings.com/mus/stories/2004/11/01/hmn_feature13. - http://www.hemmings.com/mus/stories/2004/11/01/hmn_feature13.html


Edited by pipefactory - Feb/02/2013 at 6:19am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote uncljohn Quote  Post ReplyReply Direct Link To This Post Posted: Feb/02/2013 at 7:57am
I am not sure I can add anything constructive to this thread. I have been more or less active in the AMC end of the hobby since 1979 or so and this has been an on going issue. I guess I have been under the impression it is in part a function of matching the distributor gear to the one on the cam and seems to show up after a rebuild. It is either as mentioned some form of assembly problem when putting the engine together after the fact. (The oil holes and I can not remember that being part of the issue) but probably a function of machining heads and moving the intake manifold around which then creates an issue with the height of the distributor in relationship to the cam thus changing the mesh of the gears.
And this is aggravated as memory serves by a new cam gear and possibly and old distributor gear.  I do not remember a satisfactory solution other than new parts for both or re-using the OEM parts and being careful of where the distributor ends up.
I do not think that additional oil line did anything constructive although it is a popular addition to the engine.
It seems to me that the biggest contributor to the problem was and may still be cam shaft end play. It can move foreword and backwards with in the engine block. How far it can move must be a function of gear mesh to the distributor at one end and the limit at the back of the block on the other and valve train loading on the cam shaft lobes contributing to it.
MY 1970 TSM , one of about 6 I own indicates that cam shaft end play is controlled by load placed on the cam shaft by the oil pump and distributor drive gear.  The helical cut of the gear holds the cam shaft sprocket thrust face against the cylinder sprocket thrust face thus the camshaft end play is zero during operation.
As these are all wear points and in some case a function of replacement parts and/or machining and also where the failure takes place. The problem is probably aggravated by an aggressive cam and valve train loading, the position of the distributor vertically 'specially if some one has drilled a hole in a distributor drive gear in order to install it or or possibly excessive head machining which may end up moving the intake manifold around or modifications to the oil pump.
And as many of these parts wear and are replaced, some with aftermarket reproduction parts available since the company has gone out of business.
I personally doubt oiling has much to do with it.
I rebuilt my 390 many years ago and do not remember too much about what was used. The oil pump gears came with the rebuild kit, the distributor was used over again, the cam came from Iskenderian, the cam drive sprocket was aftermarket as was the chain and the oil is 20W50. And I never had a problem.
An no, I never installed any of the oil line modifications.
I think cam walk is the biggest offender of this. How you stop it don't know.



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Post Options Post Options   Thanks (0) Thanks(0)   Quote SC397 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/02/2013 at 8:16am
This has been covered many times before.  Unfortunatly the little "search" button at the top has never worked on this forum for me very well to be able to find this kind of information.

http://theamcforum.com/forum/timing-chain_topic45911_page2.html

Did you happen to put a new timing cover on it the first time around?


Edited by SC397 - Feb/02/2013 at 8:17am
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