Proibe What is the problem and why change the spring???
Oil pressure low? If you want to increase
oil pressure, you have to increase the pump volume. The spring only controls max pressure for the motor mostly when motor
oil is cold. It stops the oil filter from becoming a rocket from under the car and an EPA mess. The spring is behind a plunger in the pump or block and bleeds off extra pressure.
The other issue is the gear in the distributor that drives the oil pump and the oil pump shaft itself. More pressure, higher volume, more stress on this part of the motor. Another thing to look at is the end play on the camshaft. If too loose on play this will accellerate the wearing out of the gears on the distributor.
If your car is on the street IMO an HVHP oil pump with an 80 psi spring will work fine. For racing an FE motor in auto cross and road racing 100 # spring in the motor. You will also need a larger oil pan, 7-8 quarts of oil in the pan.
Alot is also going to depend on what the clearances are in the motors bottom end. The tighter they are, the higher the pressure. This also depends on what oil you are running. Heavier oil will increase oil pressure 5-10 psi when hot.
Sorry Priobe the question is a good one, but not a simple one to answer, too many varibles. If you are having a problem with the motor, spill the beans. It might be something simple to repair or major and now is the time to save the motor and not explode it all over the road or track. Rick L.