Clevite MS-1265P-10 P-Series Main Bearing Set

The Clevite MS-1265P-10 is a high-performance P-Series main bearing set designed for demanding racing and performance engine applications. This main bearing set features traditional full-groove design to maximize oil flow to connecting rod bearings, making it ideal for engines requiring increased lubrication to the rod bearings.

P-Series Performance Features:

• High crush design for maximum bearing retention in the block
• Reduced overlay thickness to prevent overlay fatigue and hen tracking
• Full-groove upper bearing configuration for enhanced oil delivery to rod bearings
• Hardened steel backing for added strength and resistance to fretting
• Greater eccentricity to narrow bearing contact patterns and improve oiling
• Clevite legendary TriMetal construction for strength and durability

When to Use P-Series Bearings:

P-Series main bearings are recommended for extreme high-RPM applications where severe rod bore close-in occurs, or when rod bearing oil starvation is evident. These bearings are ideal when you need higher eccentricity to narrow bearing contact patterns and provide increased oil flow to connecting rod bearings. Signs that P-Series bearings may be needed include polishing and smearing of rod bearing surfaces with discoloration concentrated at the axial center of the bearings.

Technical Design:

Understanding main bearing groove design is critical to bearing performance. Bearings rely on an oil film developed by shaft rotation to separate the bearing from the shaft surface. The upper main shell features a 180-degree groove to supply oil to the connecting rods, while the lower shell remains ungrooved to maintain the thickest possible oil film where loads are highest. This configuration provides the best balance of oil delivery and bearing durability for high-performance applications.

P-Series bearings represent Clevite's original high-performance bearing line and are engineered specifically for competition use where maximum oil flow and high crush retention are priorities. Extra clearance versions are available for select fitting requirements.