When installing the 10778 pump in a motor running sub 5500 RPM, do you guys that frequently use this pump leave the high pressure spring in it or swap for the standard pressure spring they include with the pump? This is going into a low to mid 500hp Gen 7 496.

In those engines I use the high press spring and actually shimmed the spring to give it more pressure. The oil design in the lifter bores sucks

You should not have to shim it for your motor. If I remember right the supplied spring is 65 psi. If you feel you must shim don't go more than .030", that will put you just over 80 psi.

Remember this is where the pump relief is set, putting in a heavier spring or shimming won't do anything if your pump can't flow enough oil for your motor.

that pump,as most will make 200 plus pressure,you sure don,t want that.i use a lot of 10778 pumps and i don,t shim the spring.i test them with an oil pump dyno and they always go 65 to 70 lbs with my half inch air drill.

I didn't shim the pump, used the higher pressure spring. Looks like it maxes 70-75 psi just running on the hose after 1/2 an hour, so the oil was pretty cold.

For anyone who might care, here's my take on oil pumps, pressures and volumes. It's all about supplying the engine, mainly bearings, with enough oil to get the job done. There are a lot of factors in this but the biggest one is bearing clearances. Second being what oil you run, and clearances and oil go hand in hand. Engine usage, rpm, HP, oil temp...all play in considering clearances and type of oil. IMO volume and pressure are directly related. If you don't have enough volume to supply enough oil, then you need more volume, not necessarily pressure. This would be basically when bearing clearances are more than standard clearances and a standard volume pump isn't going to do the job. How will you know? It won't make or maintain enough pressure. Increasing pressure in a standard pump without enough volume may or may not solve the problem. Most likely not, so the next step is a high volume pump. Again, you need more oil, not more pressure. What is enough pressure? Lots of "formulas"...the oldest one in the book is 10psi for every 1000 rpm but I know too many pro level engine builders who say that doesn't work. A lot of them rate their oil pressure by HP...10 psi for every 100 hp. but that would mean for a 1200 hp build, you'd need 120 psi of oil pressure and I don't believe that either. IMO, and this is just over years of observation, in most of these sorts of marine apps if you're running a consistent 55-60# hot, WOT, full load and full oil temp, you should never have any issues. Some may like a alittle more just for insurance but remember...it takes HP to turn an oil pump and I'm never one to just throw away free HP. More pressure also increases oil temp @ the pump. To that, run whatever it takes to get whatever pressure you're comfortable with. Stock pump might be fine on a 400 hp 454. 1200hp blown wet sump with added coolers and remote filters will probably take all the oil pump you can throw at it. The more additions you have to the oil system, the more you tax the pump, and the further away these additions are from the pump, the more the pressure drop will be. A good quality pan, good oil drain back, and good, high quality full synthetic oils will also help. Keeping the oil temp under control will help and of course, good general building practices like deburring oil passages, blending entrances and exits, proper clearances and making sure the oil system is problem free will all go a long way to keeping oil pressure under control.

good post thanks

I used the 10PSI per rpm once on my old 420's per advice I got here when new at BBC, I spun 3 mains that summer 3 different times and was still told to run it that way, finally listened to my buddy Scott and used HV with shim for 80PSI and never had issues again, same with new engines I just did, with loose clearances and opened up lifters I run 20-50 and see 78 cold at idle, and at operating temp I see 25-30 at idle and 70+ running, I will give up a couple HP to MAKE SURE I have good oiling, all passages in blocks been de burred and all that also to help flow and have nice 90 degree AN fittings all over. good oiling helps long life!!

What do you shim the spring with?

My buddy got shims from local engine builder...