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  #1  
Old 11-23-2002, 06:49 AM
Al Johnson Al Johnson is offline
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Location: Cotton, MN
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I'm assembling my mild performance rebuild AMC 360 from an '84 Grand Wag. Timing set is
from PAW, their part number PAW 500. This item is a double roller chain set, made by
Dynagear, their part number 78118, as near as I can tell.

While putting this together, I was studying the oil pathway from the camshaft to the dizzy drive
gear. In the cam timing sprocket mount hole, there's a groove opposite the keyway, to let oil
through the sprocket and into the matching groove in the fuel pump cam, then into a similar
groove in the dizzy drive gear. Once into the dizzy drive gear, the oil fills a cavity in the end of
the gear, formed by the end of the camshaft, the inside walls of the dizzy drive gear, and the
heavy washer used to hold the drive gear onto the end of the camshaft. There are four small
holes in this cavity area, through the drive gear into the toothed area of the outer diameter,
to oil the pair of gears. Going back to the camshaft drive sprocket, there are radial grooves on
the front face of the hub of the sprocket which will allow oil to run out toward the cam chain
for chain oiling.

So here's the question. On the old timing gear, the original AMC piece, the oil groove on the
inside, opposite the keyway, is a full groove all the way through, so as to make lots of room
for oil to run through. On the new gear, the groove is almost all the way through, but there's
a small wall in the middle of the groove which is the same diameter as the cam nose hole, so
only a small amount of oil would ever "leak" through this area. I feel that there needs to be
quite a bit of oil flow here, to supply the timing chain and the dizzy gear drive.

So I filed the oil passage groove in the sprocket out to look more like the original sprocket.
I feel that I just saved my engine from eating dizzy gears, and very rapid timing chain wear.
Do y'all think I did the right thing? Anybody else seen something like this?

Should I let PAW and Dynagear know that I think they have a problem?

Thanks, maybe this will help somebody else, too.

Al
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  #2  
Old 11-23-2002, 11:32 AM
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Elliott Elliott is offline
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Can't tell you if you shoulda ought filed that, but I'd call the folks that made it and discuss that with them. If the original was that way I would think so.
You still won't have a lot of oil flow, so think about Performance American's oiler. Drill and tap the timing cover, run a line up from the oil pressure sending unit and then you mildly crimp the line so it just drips oil on the gear. They have a nice kit for your rear main also.
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  #3  
Old 11-23-2002, 11:46 AM
Al Johnson Al Johnson is offline
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Elliot,

Thanks for your reply. I'm trying to avoid those external oil lines if I can, and want to make the internal passages work if possible. Looks like there should be plenty of oil to the gears, if it works like it looks like it should. I've done a homemade version of the valley line to the rear main oil passage.

I think I will send a message to Dynagear and PAW, just in case they have some insight on what's up here. I doubt anybody would admit it if there's a machining operation missing, like I think there is, because then they might be liable for your fragged engine, even though the box says there is no warranty.

Anybody else seen this? It could explain some of those many distributor drive gears going south for so many people, if they're useing this timing set.

Al
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  #4  
Old 11-23-2002, 04:12 PM
RWC RWC is offline
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Location: Southcentral Alaska
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You're right on track. In preparing to do my 401 (at the machine shop right now), I've gathered a fair amount of info on AMC oiling and performance stuff. You do NOT need the external oil line; most importantly, make sure you don't mix and match your distributor/cam gears. There's a racer who said he added the external line, and then broke three distributor gears. All broken gears came out dripping with oil.

Here's the specific post I picked up awhile ago:

posted by billyrb #1581

I am in the process or rebuilding my 360, and I bought
a new double-roller timing chain (among a bunch of
other parts, some OEM, some high performance). Took it
to the machine shop with other parts to have them
prepare a shortblock for me. While it was there, a
gentleman named George Duggan (builds and races AMC's)
who is well known in the AMC world, takes a look at my
motor. He starts talking to the machine shop guys, and
notices my timing chain. He explains a problem that
90% of people don't know about......

Almost all of the lower end, and middle end, and some
of the higher end timing chain gears have a
non-operational part. You see, our timing gears are
pre-drilled at the factory to have a hole in the
center that, under pressure, forces oil to the fuel
pump lobe, and the distributor gear to keep them
lubricated. Well, a majority of those timing gears
were made at the factory as follows:

a hole is drilled partially from one side of the gear,
then another hole is drilled partially from the other
side of the gear. In theory, these two holes meet,
creating one long hole. But, alas, the holes don't
meet.

You need to inspect your new gears, and make sure that
the hole goes all the way through. The shop had to
take mine and 'tap' a hole, and file the surrounding
areas. Had George not noticed this, I would have had
premature failure on my distributor & distributor
gear, fuel pump, and other parts within a few thousand
miles.
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  #5  
Old 11-24-2002, 04:58 AM
Al Johnson Al Johnson is offline
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Location: Cotton, MN
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RWC,

Thanks for that post. I knew I couldn't be the first to notice this, but I have read extensively on this board and the AMC racer's board, and haven't heard of it before. Hope everybody reads this who is putting in an aftermarket timing set.

I sent an e-mail to Dynagear, I don't expect an answer for a couple days, then I expect the old "The inspectors must have missed that part, that's never happened before." line of BS, but we'll see. I'll let you know what kind of reply I get, if any.

Al
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  #6  
Old 11-25-2002, 12:31 PM
Al Johnson Al Johnson is offline
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Location: Cotton, MN
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Received a reply from Dynagear as follows:

Alan,

What you did was correct by opening up that passage. From time to time the foundry might
produce a casting were this oil passage is constricted during the molding process and should
have been caught in our manufacturing process.

Good catch and good luck with your AMC.

MIke

This was from MZerbe@dynagear.com.

Pretty much what I expected. They admit it might have happened once, it should have been caught, and we don't hear of any plans to try to find out if it was more than a one-time deal, or to address the manufacturing problem at the source. In other words, we really don't give a rat's patootie. I'm not terribly familiar with the sand-castin process for iron, but I'll bet if you make one bad, you made 500 bad.

So watch your cam sprockets, folks, it could be the cause of your next distributor gear failure or timing chain failure.

Al
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  #7  
Old 11-28-2002, 05:21 AM
Al Johnson Al Johnson is offline
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Location: Cotton, MN
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I'm going to bring this back to life, since I now have a drawing of the cam sprocket. This shows just the hub of the sprocket. You can see the half-round slot opposite the keyway slot. This is the oil passage I've been talking about, that must be open to allow oil to the timing chain, the fuel pump cam, and the distributor gears.

Hope this helps, and hope the link works. Thanks to my daughter for hosting the pic on her website.

Al

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  #8  
Old 11-28-2002, 08:51 AM
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Kris Kris is offline
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Quote:
Originally posted by Al Johnson:
I'm assembling my mild performance rebuild AMC 360 from an '84 Grand Wag. Timing set is
from PAW, their part number PAW 500. This item is a double roller chain set, made by
Dynagear, their part number 78118, as near as I can tell.
On the new gear, the groove is almost all the way through, but there's
a small wall in the middle of the groove which is the same diameter as the cam nose hole, so
only a small amount of oil would ever "leak" through this area. I feel that there needs to be
quite a bit of oil flow here, to supply the timing chain and the dizzy gear drive.

So I filed the oil passage groove in the sprocket out to look more like the original sprocket.

Al
I use the same gear (DynaGear), and had the same problem, and filed it also.
I wouldnt be supprised if all of their gears are like that and that more than a few slip thru.
You did the right thing
kris.
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  #9  
Old 11-28-2002, 01:15 PM
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billyrb billyrb is offline
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Location: Acworth, GA 30101
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Guys, I just picked up the post, and have to say, you are all doing the correct thing. This is becoming more of a problem, and Dynagear isn't correcting it. I bought mine last summer from PAW, and people are still getting the same problems today. Anywho, if any of you know someone in the process of rebuilding their 360, or at the very least installing a new timing chain/gear, make sure to let them know about filing the hole properly.

Also, of note, if you have your motor apart, you should consider the internal oiling mod that I did (search for oiling mod & my member #). It takes oil and adds it to the rear of the engine, specifically on #7 & 8 main bearings (where our 360's are known to fail because of lack of oil). It is about a $25 set of parts, and takes about 30 minutes to install. By the way, make SURE that you do this mod BEFORE assembling the motor, as metal shavings can fall into the engine and cause damage. If anyone has questions, email me at grand_wagoneer@lycos.com
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  #10  
Old 11-29-2002, 12:44 AM
Dan G Dan G is offline
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Location: Jersey
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FYI, Same problem exists with the Edelbrock timing chain set.
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  #11  
Old 11-29-2002, 04:07 AM
Al Johnson Al Johnson is offline
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Location: Cotton, MN
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Quote:
Originally posted by Dan G:
FYI, Same problem exists with the Edelbrock timing chain set.
Makes me think the Edelbrock set is probably made by Dynagear. Pretty odd problem to find the same thing in two different places.

Thanks for the tipoff on that.

Al
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