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V8 Oil Pump Modification Differences |
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JGRANTAMX
AMC Addicted Joined: Jun/02/2017 Location: Maine Status: Offline Points: 1697 |
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Posted: Sep/26/2022 at 8:22am |
I had this question on another members post and decided to delete that and put it up separately here. I see there are two different upper oil pump cavity modifications one has a pocket milled on one side of the gear set and the other has a slot on the other side of the gears anyone know if either of these work?
J |
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Trader
AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6881 |
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Here is a post that describes the concept in better detail but uses a different approach:
Most of the oil pressure/volume is developed on the outer teeth of the gear and pump casing. Many industrial gear pumps incorporate the "hydro relief" as it does reduce overall pumping load and also reduces the intermittent loading that you can see on with reading AMPs on an electrically driven pump of this style. The "slot" has to be a very specific size and location on the discharge side of the pump to be effective. The top picture looks to be correct, if the person doing this tested and provided the details on location and size of the slot. Don't know how practical this would be on such a small pump, but obviously people are trying/using this. The bottom picture is just plain wrong if this is what the intent was. Don't know what is going on there.
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JGRANTAMX
AMC Addicted Joined: Jun/02/2017 Location: Maine Status: Offline Points: 1697 |
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I have done the upper picture slot on three of my covers they are .010" - .015" deep I scaled the picture to get reasonably close measurements. When I was machining my covers I also bored/removed the front cover cast lip to allow seal replacement from the front. The lower picture slot I have only seen recently so I was concerned about having the right modification there.
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J |
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jcisworthy
AMC Addicted Joined: Jul/23/2009 Location: North Carolina Status: Offline Points: 2805 |
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Not sure if the lower picture was from me or not but I made the slot on the wrong side once and tossed the cover
I may have posted that picture by mistake. Don't remember
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Specializing in dyno services, engine building, and cylinder head porting
rbjracing.com Phone Number 518-915-3203 |
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Ken_Parkman
AMC Addicted Joined: Jun/04/2009 Location: Ontario Status: Offline Points: 1814 |
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I can say that that is my lawn chair. The description in Traders link is a a good one for the reason. Located correctly the slot solves the hydraulic lock problem and vents the oil to the pressure side which therefore doesn't cause any internal oil pump leaks or pressure loss. And the difference in load is significant and you can feel it when you are pre oiling. A regular drill is easily able to get full rpm and oil pressure.
I like the proper slot in the housing better; it has no leak path at all to the pump inlet. The bottom picture creates a small internal leak path and does not do a good job of venting the hydraulic lock. This stuff is well known in engineered pump design. X2 on accidentally making the slot on the wrong side once and tossing the cover.
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Trader
AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6881 |
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You could repair these covers.
Course burr the flaws, bake the oil out, rinse with acetone, fill with Loctite aluminum filler, heavy wax paper pump bowl shape, use a gear set to flatten the upper surface and squeeze the excess epoxy to the edges - rotating the gears, use sharp wood chisels to remove excess epoxy just before it completely sets, scrape off the wax paper once the epoxy is set. One relay badly scraped cover, made a 0.005" brass shim the shape of the cover bowl, baked the oil out, rinsed with acetone and set the brass shim in with Hylomar. New gears get clearance set from the bottom anyhow so adding a few thou at the top is not an issue, PO.
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Rebel Machine
AMC Addicted Joined: Jul/03/2007 Location: Western Il Status: Offline Points: 5122 |
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Mine is the same as the first photo, relief on the outlet side. -Steve- |
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JGRANTAMX
AMC Addicted Joined: Jun/02/2017 Location: Maine Status: Offline Points: 1697 |
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I rely on the knowledgeable members here when I need AMC help and info that's been priceless!
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J |
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74Bubblefender
AMC Addicted Charter Member Joined: Jun/29/2007 Location: The AMC form Status: Offline Points: 2589 |
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The gear relief channels were a concept Me and another Engineer worked on back in the late 90s. The groove will work as well but once you get past the center you really decrease your pumps efficiency. Because the oil spins around the pump and is brought to the center and that oil gets to your pump before it gets to your filter the wear on the upper part of the cavity will be much greater with less surface area and a groove to potentially move debris into the center portion of the groove. The idea is sounds but the long term resilience would mean the gear relief grooves a better choice. Fast forward 15 years and a customer in our automation side worked for Dana and accidentally grooved some gears. Was hailed as a genius and explained the concept. I showed him our gears and his face turned white. He quit Dana due to the stress of his job and the CEO showed up in his motorcade to his house in a swamp and begged him to go back to work for Dana. He refused. Nice guy, right time, right place. Interesting story. |
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We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564 |
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