21 stud, 100lb oil pressure at startup then drops

[jimTN]

Sure sounds to me as mentioned above that old bearings were used and as the engine warms up, excessive clearance drops the oil pressure.

[rotorwrench]

A person can modify for a restrictor in there so it would still flow some oil to the cam chamber. I would sure recommend that if a person was going to eliminate the relief valve. Most folks just leave it alone. The relief valve springs do fatigue with time so replacing it at overhaul is not a bad idea. I just wonder if there is a tension to height specification for those springs so a person can check them for fatigue.

[41ford1]

Originally Posted by rotorwrench

A person can modify for a restrictor in there so it would still flow some oil to the cam chamber. I would sure recommend that if a person was going to eliminate the relief valve. Most folks just leave it alone. The relief valve springs do fatigue with time so replacing it at overhaul is not a bad idea. I just wonder if there is a tension to height specification for those springs so a person can check them for fatigue.

Here is that information from a '48 manual:

Oil Pressure Regulator Relief Valve-Check relief valve spring tension and replace spring if tension is less than 78 ozs. or more than 87 ozs. when

compressed to length of 1.380".