Adjustable Oil Pressure Regulator, #2010A

 Builders:

Below is a photo of a part I have developed for Corvair flight engines. I have long thought about making this, but it took a while to come up with something which could be made affordably, which would still do the task without any possibility of reducing the reliability of the oil system. Below is the end result, and in our numbering system, it’s designation is #2010A, it is part of the Group 2000, rear oil case components.

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Above is the 2010A installed on Phil Maxson’s 3,000cc Corvair. You can read the story of building this engine at this link: Phil Maxson goes to 3,000 cc for his 601XL.

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The normal running oil pressure on a stock Corvair car is 37 psi. Anytime the engine is above 1800 rpm or so, the engine will normally run at its regulated oil pressure, set by the spring working against the small piston in the rear oil cover.

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This pressure is slightly below what I prefer for aircraft engines. I would rather see 42-48 pounds on flight engines. More is not better, it is unnecessary stress on the drive system, and no one should be using number in flight like 60 pounds at warm cruise. The typical way to get a number in the range is to change the spring. The issue is that the aftermarket springs are far too strong these days, and often make motors run at 60 psi or more.  The best solution is the adjustable pressure regulator.

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This works by having a screw thread which preloads the pressure spring. On Phil’s engine, I noted on the first run the engine was regulating the pressure at 36-38 psi. Phil said this is how it normally ran. (The high volume oil pump has no effect on the regulated oil pressure, just the pressure spring and piston do.) If I had simply put in a high pressure spring, it would have likely seen 60 psi, too much. Instead, I put in the #2010A unit with the stock spring, and ran the engine again. With the engine warmed up and running, It took less than 30 seconds to dial in 46 psi right on the money.

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The guts of the unit are very simple, but the internal measurements are not. One of the critical issue that took a bit to figure out was how to make the unit so that even if it backed off entirely, the pressure would never drop below the stock 37 psi number. The other issue is the dimension of the plunger that applies the screw pressure to the spring. It can not hang up in the bore, but neither can it get into the spring ID. I worked this out over a lot of testing on the rig seen below. I would like to gather a bit more operational data, but eventually we will release part # 2010A to builders.

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Grace out in the shop. This is or rear oil test rig, if you would like to rear a longer story about how it works, check out this link: High Volume Oil Pump.

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