King Engine Bearings MB4577SI SI-Series Main Bearing Set

King Engine Bearings MB4577SI is a precision-engineered main bearing set from the SI-Series line, designed for OE replacement applications in gasoline and diesel engines. This bearing set is ideal for aftermarket engine rebuilding and performance engines utilizing factory crankshafts.

Key Features:

• SI-Series K-788 aluminum-based bearing material strengthened with 2.5-3% silicon
• Optimized for medium load engines and nodular cast iron crankshafts
• Improved crankshaft finish reduces microscopic ferrite peaks on improperly ground or polished crankshafts
• Enhanced oil clearance design reduces wear and extends engine life
• Ultra-tight bearing wall thickness tolerance of ±0.0001 inch for precision fit
• Reduces operating noise, vibration, and excess oil flow
• Lead-free construction for environmental safety
• Steel backing with precision-finished bearing surface

King Engine Bearings specializes exclusively in engine bearing production, applying race-proven technology and rigorous quality control to every bearing set. Each bearing undergoes multiple quality checkpoints throughout the manufacturing process to ensure consistent performance and durability in demanding applications.