King Engine Bearings MB5184SI 020 SI-Series Bi-Metal Main Bearing Set GM 262 302 327 350 Flange +.020

The King Engine Bearings MB5184SI 020 is a complete SI-Series bi-metal main bearing set engineered for General Motors small-block V8 engines. This is a flange (FL) bearing set with a +.020" oversize thrust, designed specifically for crankshafts that require regrinding of the thrust surface.

Built on King's proven SI-Series (K-788) bi-metal construction, these bearings use an aluminum base alloy strengthened with 2.5–3% silicon. This formulation delivers excellent strength and wear resistance, making it the ideal choice for medium-load engines and engines equipped with nodular cast iron crankshafts. The silicon content improves the bearing's ability to handle the microscopic ferrite peaks common on improperly ground or polished nodular iron journals.

Key Features:

• SI-Series Bi-Metal construction — 100% lead-free aluminum-silicon alloy on a steel backing
• Flange (FL) design with +.020" oversize thrust — allows repair of worn crankshaft thrust surfaces without replacing the crank
• Improved oil clearance — engineered to reduce wear, minimize operating noise and vibration, and control excess oil flow
• Improved crankshaft finish compatibility — reduces microscopic ferrite peaks on nodular cast iron crankshaft journals
• Bull's Eye Tolerance™ — bearing wall thickness held to ±.0001" for precise, consistent fitment
• Lead-free material — environmentally responsible and safe for engine rebuilders
• Recommended for OE replacement and aftermarket gasoline engine rebuilding applications

King Engine Bearings has specialized exclusively in engine bearings since 1960, manufacturing every product under one roof with multiple quality control checkpoints throughout the production process. The MB5184SI 020 set is an excellent choice for engine rebuilders seeking a reliable, precision-fit main bearing solution for GM small-block applications with a reground crankshaft thrust surface.