This device screws into the side of the rear oil case in place of the #2010 plug. It has an internal allen screw thread which preloads the pressure spring, making the regulated pressure adjustable, even on a running engine.
Stock Corvair oil pressure regulates at 36-38 psi. (The high volume oil pump has no effect on the regulated oil pressure, just the pressure spring and piston do.) If I simply put in a high pressure spring, see 60 psi, which I consider too much. Instead, I put in the #2010A unit with the stock spring, and ran the engine again. This part allows fine tuning the pressure to anything the builder desires.
I have hand built a dozen of thise units, and they are flying on a number of planes like Phil Maxson’s 601XL and Bob Lester’s Pietenpol. They are time consuming to hand make, but through CNC production, we will bring the cost down to a reasonable level.