P Series Main Bearing Set STD Suit Ford Flathead 1939-53 239, 235

P-Series Bearings

These are not to be confused with the standard passenger car and light truck parts for the same retention applications which also have a "P" suffix letter. These high performance parts have unique core part numbers different from the standard parts for the same application. P series parts are the oldest series of Clevite high performance bearings. The rod bearings in this series typically have the greatest amount of eccentricity. Most rod bearings are available either with or without dowel holes for use in aluminium rods. Most P series main sets are full grooved to maximise oil flow to the rod bearings. Both rods and mains have high crush for maximum retention, and a reduced overlay thickness to prevent overlay fatigue, sometimes referred to as hen tracking.

Rod bearings use a hardened steel back for added strength and resistance to fretting. clearance rod bearings are available for .001" additional clearance and select fitting. Use the P series rods where extremely high RPM's cause severe rod bore close-in. This is typically indicated by nearly full parting line to parting line shaft contact with bearings having less eccentricity. Use P series mains where higher eccentricity is desired to narrow bearing contact patterns and to provide increased oiling to rod bearings. Rod bearing oil starvation is typically indicated by polishing and smearing of the bearing surface, possibly accompanied by discolouration predominantly concentrated at the axial center of the bearings.