Clevite MS-2273A AL-Series Engine Crankshaft Main Bearing Set

The Clevite MS-2273A is an AL-Series engine crankshaft main bearing set engineered for reliable performance in OEM-style rebuilds and mild performance applications. This set features 100% lead-free aluminum silicon (AL-5) construction with a half-groove (180°) design in the upper shell — the optimal configuration for balancing oil film integrity with proper lubrication delivery to connecting rod bearings.

Clevite's AL-Series bearings are built around the principle that for many engines, particularly those running cast crankshafts, the softer and more conformable nature of an aluminum alloy bearing provides advantages over stiffer steel-backed alternatives. The carefully selected eccentricity is tailored to the specific application, ensuring consistent journal contact patterns and dependable long-term performance.

Key Features:

• AL-5 aluminum silicon material — 100% lead-free construction for modern engine compatibility
• 60% more silicon than comparable competitive replacements for superior journal surface conditioning
• Half-groove (1/2) upper shell design — maintains a robust oil film on the lower shell while supplying oil to rod bearings via the upper groove
• 100% bored inside diameters for optimum surface characteristics and consistent precision fit
• Application-specific eccentricity engineered to deliver solid, reliable bearing contact patterns
• Greater seizure and wear resistance resulting from the high-silicon aluminum alloy formulation
• Recommended by Clevite for engines using a cast crankshaft
• Sold as a complete set

The half-groove upper shell configuration represents the ideal balance in main bearing design — the upper shell retains a 180° groove to channel pressurized oil to the connecting rod bearings, while the ungrooved lower shell develops a thicker, more stable hydrodynamic oil film for the crankshaft journal to ride on. This design maximizes bearing life and provides a greater safety margin under load. The Clevite MS-2273A is an excellent choice for stock rebuilds and mild performance builds requiring a dependable, high-quality OEM-style replacement main bearing set.