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Distributor Drive and ZDDP |
Post Reply | Page 123 7> |
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Rebel Machine
AMC Addicted Joined: Jul/03/2007 Location: Western Il Status: Offline Points: 5121 |
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Posted: Oct/22/2018 at 5:54pm |
Took the distributor out of my AMX's 401 and found this: Been running Mobil 1 10W30 synthetic, wondering if a ZDDP additive would have prevented this. -Steve- |
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FSJunkie
AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4742 |
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ZDDP doesn't do anything to help distributor gears. There is not enough pressure present where the gear teeth mesh to activate the Zinc and Phosphorus. Gear failure like that is usually caused by not verifying the oil path to the distributor drive gear or a timing cover that is misaligned or manufactured poorly.
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1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
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Rebel Machine
AMC Addicted Joined: Jul/03/2007 Location: Western Il Status: Offline Points: 5121 |
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I verified the oiling by using a modified timing cover and running the oil pump with a drill. I'm certain there was no problem there. Funny thing, every time I came back from racing the car wouldn't idle right. Noticed the timing had retarded a bit so I'd bump it back up. Clearly this is due to the wearing distributor gear. Appears this problem was accelerated by high-rpm use at the track. I'm going to see my engine builder this afternoon and see if he's got some insight. -Steve-
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Trader
AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6913 |
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With that much track time you will likely want a bronze gear or composite and be changing it every year, have a read:
I believe our gears are the same profile and dimensions as Ford's so a replacement for your purposes should not be that difficult. Just a PITA.
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PHAT69AMX
AMC Addicted Joined: Jul/07/2007 Location: West Virginia Status: Offline Points: 5926 |
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What a bummer... sure you've seen all the discussions about'em...
Obvious question(s), what Distributor and what brand of gears ? OEM AMC ?
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Greyhounds_AMX
AMC Addicted Joined: Nov/14/2009 Location: Kansas City Status: Offline Points: 1268 |
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Steve, could you measure the side to side clearance at the lower bushing of the distributor?
I'm wondering if some of the gear wear issues we see could be related to lower bushing wear allowing the gear to move out of the correct relationship with the cam gear.
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1968 AMX 390 w/T5
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Trader
AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6913 |
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If you take a good look at Steve's gear picture you can do some analysis just as you could a differential gear set.
There is no root wear and the worn area is were it would be expected, a lot of it mind you. You can see were the cam gear must be sitting by the curve and it's slightly high but well within tolerance for acceleration. The most wear seems to be on the "acceleration face" of the gear. You can also see deceleration wear but more so at the bottom of the gear so the end play of the distributor is a bit excessive. The gear is either not getting enough lubrication or just plane worn out from abuse. From Steve's description of use I'd tend to think it's abuse. The ZDDP of the oil is adequate for street use. This use I would think needs a race oil and that may have helped some. Steve, how does the cam and lifters look. I'd pull a cover, couple of lifters out to have a look. Just to ensure your OK there.
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scott
AMC Addicted Joined: Jul/10/2007 Location: Wildwood Pa. Status: Offline Points: 3502 |
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Where did you get the gears you were running on the distributor & cam?? Google AMC distributor gear problems, you'll have hours & hours of reading.
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Mopar_guy
Supporter of TheAMCForum Joined: Jun/07/2009 Location: Ohio Status: Offline Points: 4837 |
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To me it looks like it wasn't heat treated right. It's softer than the cam gear is.
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"Hemilina" My 1973, 5.7 Hemi swapped Javelin |
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tomslik
AMC Addicted Joined: Mar/07/2008 Location: Colorado Status: Offline Points: 680 |
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i'm wondering how much oil pressure you're running?
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67 american 290/4speed |
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