King Engine Bearings MB5877SI 020 SI-Series OE Replacement Main Bearing Set GM Vortec LS Gen III IV

The King Engine Bearings MB5877SI 020 is an OE-replacement main bearing set engineered for GM Vortec and LS-Series Gen III and Gen IV engines. This set is supplied in the .020" undersize journal dimension and features a Standard (STD) flange, making it the ideal choice for engine rebuilds where the crankshaft main journals have been ground .020" undersize.

Manufactured using King's proprietary SI bi-metal material, these bearings combine an aluminum alloy laced with 2.5–3% silicon on a steel backing. This construction delivers excellent strength, conformability, and embedability — ideal for medium-load engines, particularly those equipped with nodular cast iron crankshafts. The SI material is completely lead-free, meeting modern environmental and performance standards.

Key Features:

• OE-replacement bi-metal SI construction — aluminum alloy with 2.5–3% silicon on steel backing
• .020" (020) undersize journal dimension for reground crankshafts
• Standard (STD) flange thickness — 5 pairs included per set
• Lead-free bearing material for environmental compliance and superior performance
• Designed for medium-load applications, especially with nodular cast iron crankshafts
• Shaft journal diameter: 64.993–65.007mm (2.5588–2.5593")
• Tunnel (housing bore) diameter: 69.873–69.886mm (2.7509–2.7514")
• Compatible engine families include: LS1, LS2, LS3, LS7, LM7, L76, L77, L98, and related GM Vortec V8 variants

King Engine Bearings maintains bearing wall thickness tolerances to an industry-leading ±0.0001", ensuring precise oil clearances and consistent performance across every set. Whether you're completing a stock refresh or a performance rebuild on a GM Vortec or LS-platform engine, the MB5877SI 020 delivers the reliability and precision that professional engine builders trust.