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Mandatory oil system mods |
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Rebel Machine
AMC Addicted Joined: Jul/03/2007 Location: Western Il Status: Offline Points: 5122 |
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The oiling passage in all the aftermarket cams and timing gears needs
to be checked. The front cam journal supplies a path for oil going to
the distributor drive gear. Many times the timing gear has that groove
in the wrong place or the groove extends beyond the diameter of the
cam's front journal. This is a comparison of an aftermarket cam gear (left) and an original AMC gear (right). You can see the aftermarket gear groove extends well beyond the distance of the original gear. The arrow shows the timing gear groove extending past the cam journal diameter causing a loss in flow going forward to the distributor drive gear. I've welded and machined the timing gear to fix that. |
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scotty54
AMC Apprentice Joined: Aug/07/2015 Location: TN Status: Offline Points: 70 |
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This is the first I have heard of the extra quart. Any issues with the depth of the stock pan and frothing? Do the compacts have a different pan that may preclude the extra quart?
I have always done the oiling mods originally recommended by Performance American Style and never had a bearing fail. But it appears that those who don't do the mods haven't had a fail either. Great info in this thread!
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Trader
AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6881 |
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The extra quart was a thought up patch early on as people thought the problem with the AMC motor was too much oil being pumped to the top of the cylinder heads and that caused the oil pick-up to catch air.
Modern thinking and track proven is oil aeration being the big problem, oil frothing in the crankcase and picking up air. The extra quart would actually aerate the oil more as the crankshaft spins through the excess oil. This air/oil mix would then be pumped through the engine and not lubricate near as well as straight oil. Air separation in the top of the engine can cause even more problems if not achieved in the valley or rockers. An extra quart oil pan reduces aeration of the oil and also provides for "spirited" driving as oil is pushed front to back or side to side. The stock pan with stock oil level is good for every day driving.
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PHAT69AMX
AMC Addicted Joined: Jul/07/2007 Location: West Virginia Status: Offline Points: 5919 |
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Previous thread with Oiling info and Diagrams:
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bobsterfl
AMC Nut Joined: Jun/18/2009 Location: Orlando, Fl Status: Offline Points: 261 |
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Lots of good advice in all these posts.
I am old enough to remember AMC being involved in the Trans Am racing series, and have read numerous articles over the years describing blown-up engines due to oiling problems. Of course, these cars were revving high and experiencing really high g-forces in hard cornering. The final ultimate fix was to change over to a dry sump, belt driven external pump with a large external oil tank, very similar to what NASCAR uses today. That would be overkill for most of us.
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Bobsterfl
1970 BBO Javelin 390 - Torqueflight |
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Boris Badanov
AMC Addicted Joined: Dec/14/2013 Location: NH USA Status: Offline Points: 4209 |
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The crank is in the oil at start up and an extra quart exaggerates the issue.
Oil return is marginal in an AMC because of small return openings in the heads and the collection of oil in hard acceleration in the lifter gallery area. Stock umbrella seals broke up and the debris blocked the returns and cause general mayhem in the oil system. Yes, I have seen a number of AMC V8s that had oil pressure only until the oil was all pumped to the valve covers. Sludge and umbrella seal debris slowed the return. Wait a few minutes and re-start and oil pressure was back. For a few seconds..... The plastic button on the oil pick-up had a similar effect. The button becomes dislodged and the pick up goes flat against the bottom of the pan. AMC V8 is a great motor when all is well, any motor fails with no lubricant.
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Gremlin Dreams
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19676 |
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I don't have the supporting documentation any more, and can't remember where I even got it, but the AMC Gen2/3 V-8 was designed for six quarts from the start. Six quarts are specified for police and heavy duty fleet use (taxis and such) -- and they use the SAME OIL PAN STAMPING. The police pan has a rudimentary baffle to keep oil from being sloshed to the front in hard stops, that's the only difference (don't know if the HD/Fleet pan is the same as police or just a standard pan). Marketing cried that a six quart oil change would make AMC engines more costly to maintain than the competition, so it was tested and found that five quarts was sufficient for normal driving, so the owners manuals state five quarts -- same as everybody else in that era. The valley line was introduced by drag racers to help with oil starvation under hard acceleration to the rear main and rod bearings. Basically it just supplies extra volume by having another path. I think it is an aerated oil issue -- the oil gets sloshed hard enough to the rear of the pan and a lot of oil is quickly sucked up out of the pan, allowing a little air to be sucked in at the pickup. The twin paths increase the amount of oil, and should reduce aeration. I don't think it's necessary except on those really quick drag cars -- not your usual weekend bracket racer. You have to be pushing the engine near it's limits to make extreme mods like that, and I mean really built up to near max possible output. Building a 10 second or less 1/4 mile car? You might need it.
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Frank Swygert
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Rebel327
AMC Nut Joined: Jan/26/2014 Location: Toledo Ohio Status: Offline Points: 358 |
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I believe someone posted pic of the 6th quart in pan. Considering the extra volumn and the additional minimal depth of oil as it is spread about the surface area...aeration is not an issue. The extra volumn creates no harm but instead provides several benefits. Wish I could remember who posted pic. I think he has built over 100 AMC V-8's..
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Trader
AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6881 |
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I have made all my oil pans 6 Quarts since 2012 but have not built 100's of engines.
I remove the standard pan baffle, hammer and dolly the back of the pan to an outy and not an inny and re-install the standard baffle. Next pan to do: |
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Red Devil
AMC Addicted Joined: Jul/10/2007 Location: Canada Status: Offline Points: 1743 |
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Deja-vu ... check a few posts down for more discussion on pans & capacity.
Quotes from that thread posted by Steve P, an actual Engineer who worked at AMC:
X2 his post in this thread to fit an Aviaid pan or similar. I've got an Armando pan on my 401 (very similar to the Aviaid as Armando used to work for them). Hope this helps,RD
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