King Racing Main Bearings – 5M8309H Series (STD, 0.025, 0.25, 0.50) King Racing 5M8309H Main Bearings are engineered for high-performance engines requiring exceptional durability under extreme RPM, heat, and load. Manufactured with advanced tri-metal construction and an F780 material overlay, these bearings offer unmatched fatigue resistance, precise clearances, and improved heat dissipation. This set is designed for engines running high power and revving hard, with features like 3/4 grooved main journals for better oil flow and enlarged chamfers to suit aftermarket crankshafts with large fillet radii. Key Features High-performance tri-metal bearing design F780 alloy with high-strength overlay for extreme fatigue resistance Hardened steel back for maximum support and housing retention 3/4 groove design improves oil flow to conrod bearings Increased crush and consistent wall tolerances for optimal fit Enlarged ID chamfers to accommodate performance crankshafts Eliminated flash plating for enhanced heat transfer and grip Technical Specifications (STD Size) Specification Value Material F780 Tri-Metal Oil Clearance Factory Spec Min. Std Shaft Size 59.984 mm Max. Std Shaft Size 60.000 mm Min. Std Tunnel Size 64.000 mm Max. Std Tunnel Size 64.020 mm Max Wall at Crown 2.005 mm Overall Length 22.92 mm (8309H) Half Type Identical Halves Available Sizes STD, 0.025, 0.25, 0.50 Applications High-performance and motorsport engine builds Suitable for engines using King 5M8309H-series main bearings Note: For engines requiring additional oil clearance, HX versions are also available (e.g., 5M8309HX). Warning: This product may contain materials such as Nickel (Metallic), which are known to the State of California to cause cancer and reproductive harm. See Proposition 65 Warnings for more details.
