King Engine Bearings MB5231AM0.5 AM-Series Main Bearing Set Oversize - 0.50mm

The King Engine Bearings MB5231AM0.5 is an AM-Series crankshaft main bearing set designed as an OE replacement for Nissan L13, L14, and Z18 engines. This set features a +0.50mm oversize crankshaft undersize, making it suitable for engines that have had the crankshaft journals reground to that specification.

Key Features:

• AM-Series Bi-Metal Construction: Utilizes King's standard aluminum-based (Alecular silicon) material — the softest bi-metal in King's range — engineered for passenger car engines with low to medium loads
• Superior Embeddability: Provides greater macro-particle capacity to reduce scratching of crank journals and minimize tearing or weakening of bearing overlays
• Precision Tolerance Control: Manufactured to within ±0.0001 inch for consistent, reliable fitment and proper oil clearance
• Lead-Free Material: Environmentally safe, lead-free composite bearing material for both user safety and ecological responsibility
• Full Groove Design: Features grooves on both upper and lower bearing halves for optimal oil distribution
• Maximum Thrust Bearing Oversize: Includes appropriately oversized thrust bearing to complement the reground crankshaft

The King AM-Series is the ideal choice for OE-replacement applications, recommended for street and marine use. King Engine Bearings has been a trusted name in precision engine bearings since 1960, offering tight manufacturing tolerances and quality materials that protect crankshaft journals and extend engine life.