Clevite MS-1266A-10 Engine Crankshaft Main Bearing Set

The Clevite MS-1266A-10 is a high-performance engine crankshaft main bearing set designed for demanding automotive applications. This precision-engineered bearing set features Clevite's proven TriMetal construction, combining a steel backing with a copper-lead intermediate layer and a lead-tin-copper overlay for exceptional strength, durability, and wear resistance.

Understanding Main Bearing Design:

Modern main bearing technology focuses on optimizing oil film thickness to maximize bearing life. This bearing set features a 180-degree groove in the upper main shell, which provides optimal oil delivery to connecting rod bearings while maintaining maximum oil film thickness in the loaded lower bearing shell. This design has been extensively tested and proven to deliver superior performance compared to full-grooved or extended-groove configurations, resulting in lower peak oil film pressures and reduced horsepower loss.

Key Features:

• TriMetal construction with hardened steel backing for maximum strength
• Lead-tin-copper overlay with optimized thickness to prevent fatigue
• 180-degree upper shell grooving for efficient rod bearing lubrication
• Ungrooved lower shells for maximum oil film thickness and load capacity
• High crush design ensures positive bearing retention
• Precision manufacturing for consistent clearances and performance
• Suitable for performance and racing applications

Performance Series Options:

Clevite offers multiple bearing series to match specific engine requirements. The P-Series features maximum eccentricity and full grooving for extreme RPM applications with rod bore close-in issues. The H-Series provides medium eccentricity with enlarged chamfers for oversized crankshaft fillets, making it the recommended starting point for most performance builds. The K-Series adds a proprietary moly/graphite TriArmor coating for enhanced protection during start-up and high-load conditions. The V-Series utilizes lead-indium overlay for improved conformability, while the M-Series features thick babbitt lining for applications with severe crankshaft deflection.

This main bearing set is engineered to deliver reliable performance in both street performance and competitive racing environments where bearing durability and consistent oil film protection are critical.