King Engine Bearings MB5234SI0.25 SI-Series Main Bearing Set Undersize - 0.25mm

The King Engine Bearings MB5234SI0.25 is a precision-manufactured main bearing set designed for engine rebuilding and restoration applications. This SI-Series bearing features a 0.25mm undersize specification for use with reground crankshafts.

SI-Series Construction:

• Bi-metal aluminum-silicon alloy construction strengthened by 2.5-3% silicon content
• Lead-free design for environmental safety and user protection
• Designed specifically for medium-load engines and nodular cast iron crankshafts
• Improved crankshaft finish compatibility reduces microscopic ferrite peaks on improperly ground or polished crankshafts

Performance Features:

• Bulls Eye Tolerance with all shells matched to 0.0001 inch for precision fitment
• Enhanced oil clearance design reduces wear and increases engine life
• Reduces operating noise, vibration, and excess oil flow
• Suitable for OE replacement applications and performance engines with factory crankshafts

King Engine Bearings has been manufacturing premium engine bearings since 1960, specializing exclusively in bearing production. Every bearing is produced entirely in-house from casting through final packaging, ensuring complete quality control throughout the manufacturing process. King bearings are engineered for both street applications and high-performance racing engines.