Building a GMC 702 V-12

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(Pay Attention 2)
(Pay Attention 2)
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Your larger gerotor oil pump may also have the hydraulic governor as part of it. If it does it is a stand-off chamber below the main pump that is fed oil thru the center of the shaft. You will see a spinner that open a valve in the hollow connecting shaft inbetween the chamber and the main pump body. The good news is that you shall remove all of this and toss it. You can not easily perform the mods to this bottom gerotor plate as it is a casting of sorts. Which I had a pic but that got tossed. So if you have this governor BS thingy then unbolt it and get a plate from another pump. You can also make one as they are only 1/4 inch flat mild steel.
 
Your larger gerotor oil pump may also have the hydraulic governor as part of it. If it does it is a stand-off chamber below the main pump that is fed oil thru the center of the shaft. You will see a spinner that open a valve in the hollow connecting shaft inbetween the chamber and the main pump body. The good news is that you shall remove all of this and toss it. You can not easily perform the mods to this bottom gerotor plate as it is a casting of sorts. Which I had a pic but that got tossed. So if you have this governor BS thingy then unbolt it and get a plate from another pump. You can also make one as they are only 1/4 inch flat mild steel.
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Here is what the one you want looks like (Ignore the "peanut cutout" as I will get into that in a minute here)
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[[File:Plate.jpg]]
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To help understand what we are trying to do, if you have your pump disassembled and look up into the housing you will see the port for the vacuum side of the pump. Notice its tapering shape and orientation. We seek to create a mate to that on the bottom side and provide relieve in the form of a lubrication pocket on the pressure side opposite the top pump exhaust (where the oil is under pressure and sent to the distribution. This force on the top side of the gerotor causes the bottom of the rotor to wear under, just look at the scoring on your bottom plate and you will see evidence.
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Here is a custom Titan lower plate (ignore the center bearing as that is intended for support at very high RPMs and I did not seek to replicate that for this project though it would not hurt it would take some doing to get a stub shaft onto the bottom of the gerotor).
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[[File:bare_titan.jpg]]
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Notice the shapes are similar to the GMC.

Revision as of 16:50, 15 May 2011

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