Clevite MS-1668P-.25MM Main Bearing Set Undersize Performance

The Clevite MS-1668P-.25MM is a high-performance main bearing set designed for demanding racing and performance engine applications. This .25mm undersize bearing set features Clevite's proven P-Series design, optimized for extreme RPM conditions and maximum oil delivery to connecting rod bearings.

P-Series Performance Design:

• Full groove configuration in upper shells maximizes oil flow to rod bearings
• High eccentricity profile narrows bearing contact patterns for improved performance
• Maximum crush design ensures superior bearing retention under extreme loads
• Reduced overlay thickness prevents overlay fatigue and "hen tracking"
• Hardened steel back construction provides added strength and fretting resistance
• Engineered without flash plating for optimal bearing seating

Advanced Bearing Technology:

Clevite's P-Series bearings utilize a time-tested TriMetal construction that balances durability with performance. The 180-degree groove in the upper main shell provides the optimal balance between oil film strength and connecting rod lubrication. This design maintains maximum oil film thickness in the loaded lower bearing half while ensuring adequate oil supply to the rods.

Ideal Applications:

• High-RPM racing engines experiencing severe rod bore distortion
• Applications requiring increased oil delivery to rod bearings
• Crankshafts worn .25mm undersize or ground to this specification
• Competition engines where rod bearing oil starvation is a concern

When to Choose P-Series:

Select P-Series main bearings when you need higher eccentricity to narrow contact patterns and provide increased oiling to rod bearings. These bearings are particularly effective in engines where rod bearing oil starvation is indicated by surface polishing, smearing, or discoloration concentrated at the bearing's axial center. The high eccentricity design helps prevent the severe rod bore close-in that occurs at extremely high RPMs.

This bearing set represents Clevite's oldest and most proven high-performance bearing series, trusted by engine builders for decades in the most demanding racing applications.