Today I noticed that the op was arround 70 as I was driving off with a cold engine.
It then settled at 38 at idke and 58 at 3000.
I had this same situation on another XK, and changed the spring under the op relief valve. That lowered the pressure to more normal figures.
I dont recall having these high figures on this 120 before. The other car always had too high readings after engine rebuild.
What could have happened to this engine, that suddenly raised the op?
If you know for dead certain that the oil pressure gauge is accurate and has remained consistent, about the only thing that can dramatically change oil pressure in either direction is the pressure relief valve. If it leaks, the pressure can drop and if it sticks closed, cold pressure will be high.
The other possibility is the gauge. The needle is pushed onto a shaft and can work itself loose and move, giving inaccurate readings. Not very common but it did happen to me once.
The needle of the op gauge is nicely parked against thestop needle. I took some pictures of the nonoriginal engine with its odd looking Tecalemit oil filter house.
Cant see where access to the relief valve is
Perhaps tap the filter housing with a suitable tool, while the engine is idling, and hope for the stuck valve to open…