The oil pressure on my front engine was 20psi lower than rear engine on same settings.
Location of oil pressure relief valve is on pilot side > accessory case > adjacent to alternator. It has safety wire and is a 1 1/8” socket fitting.
2 ways to adjust
1: Older engine were not adjustable. There is only a long spring and it needs to be replaced to get the proper resistance required. With that said, When i removed mine there was a “hack” where the spring meets the cap, someone before my ownership placed 3 washers between the cap and spring. This added the needed resistance to create proper pressure. Im guessing this is not the first time pressure was low.
2: TCM makes a replacement adjustable oil relief valve. The spruce sells it and as of today the parts total about $600. Ive attached photos of the parts diagram.
https://ibb.co/gMYKhsF
https://ibb.co/gtw73v7
https://ibb.co/H2LgNyx