I am wanting to get 10 more oil psi, how much shim thickness should I add to the spring to get that 10 psi wanted?

That is a HV & HP melling oïl pump with HR 15/50 driven racing oïl, .003 main and .00275 rod clearance.

You will need about .030 of shim to raise it about 10 psi. You can use a thin #10 washer. It should get you where you want.
Eddie

I did the same thing Eddie recommended. Tapped the plug down a bit until the washer was flush with the oil pump housing and bolted her up.
I got the tip from my machinist.

just don't overdo it. i shimmed the pump in an old dodge slant six a million years ago. gauge went to the pin and the oil filter exploded 2 seconds later...

Not clear on what you did ...Spring on a Melling is held in with rollpin?

LMAO..

Thanks for info, i will test the perssure with mec gauge before reinstall in the boat, just in case i have too much pressure after shiming the spring.

Just curious, what are you current pressures? Have you verified that the gauge is reading accurately? Some builders are starting to suggest that running extremely high pressures is not necessary. I'm running the same clearances on my rods and mains, so this thread interests me. I have read that thicker oils and high pressure can cause a lot of wear on the distributor gear.

Good luck with it.

Yes i have verified my gauge and the reading is right.

Coold pressure is at 68-70 psi in running , and drop at 48-50 psi in hot situation, i see that drop i think is when the oïl t-stat is open and the oïl is passing into the oïl cooler, so i want to gain 10 psi that would give me 60 psi in hot running situation.

oïl pump is melling 10778 (HV-HP)

Some folks may disagree with me, but I would not be scared to run those pressures. I ran a mild 454 for over ten years with a standard volume pump and had hot oil pressure on the order of 45 PSI, and the bearings looked fine when I pulled it apart for a different issue. Now if you are running a boosted application or something high compression way out on the edge of performance, then I could see wanting a little more pressure. Lots of differing opinions on this, and I don't want to stir any controversy, but thought I would toss out my experience in case it could help.