View Full Version : HRC oil pump gears

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10-05-2006, 12:21 AM
This is our "HRC" idler gear

This gear is equipped with hydro relief channels (HRC)

As you can see in pic 1 you will notice the small grooves in the idler oil pump gear. In pic 1 shows the beginning of the normal AMC oil pump rotation. AMC oil pumps turn counterclockwise (when facing the bottom of the gear) and bring the oil around the pump cavity. The gears come together and force the oil out the opening at the top of the pump cavity. Notice the circled area...this area will shrink when the gear spins


Here we see in pic 2 the area has shrunk and this causes a tremendous amount of pressure between the gears. Hydro relief channels are taking effect now and pushing the extra pressure between the gears to the output side of the oil pump and relieving the tremendous pressure between the gears.


In pic 3 we see the next area above the first starting to shrink and building pressure. The area below is opening up and causing a small suction. Here we see the hydro relief channels doing their job once again relieving the tremendous pressure yet again from the other side.


This cycle starts over again with the idler gear side as shown in pic 1. These gears with HRC's cause less wear on the distributor gear and camshaft gear (which drives the oil pump) and less wear in the pump and on the gears caused by this pressure pushing and pulling the gears at different RPM's and throttle changes. These gears can also give 20% less wear in the pump cavity due to relieving the pressure between them. While not 100% of the pressure is relieved it is substantial.

You can find these in our E-store shortly.

04-23-2017, 01:33 PM
Have you noticed any significant loss in overall oil pressure?

04-24-2017, 02:02 PM
Gain in pressure not loss. You will get a loss if you put the grooves up towards the top of the motor

09-21-2022, 04:34 PM
Are the HRC gears compatible with the stainless midplate?

01-17-2023, 03:16 PM

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