King Engine Bearings MB557XPC020 XP-Series Coated Tri-Metal Main Bearing Set 0.020 Undersize

The King Engine Bearings MB557XPC020 is a premium XP-Series coated crankshaft main bearing set engineered for high-performance and racing applications on General Motors small block engines. Featuring King's advanced pMaxKote™ nano-composite polymer coating technology, this set delivers exceptional load capacity, wear resistance, and protection under extreme operating conditions.

XP-Series pMaxKote™ Construction:

• Tri-Metal Base Structure: Enhanced copper-lead construction with a nickel barrier and SecureBond™ adhesion process for superior layer-to-layer stability and structural integrity
• pMaxBlack™ Overlay: A proprietary surface-hardened lead-tin-copper overlay electroplated onto the copper alloy substrate, achieving up to 10,200 psi load capacity — 24% greater than conventional tri-metal race bearings
• pMaxKote™ Top Coat: A factory-applied nano-composite polymer coating containing ceramic nano-composite particles that act as a fourth functional layer, enhancing wear resistance and protecting bearings during metal-to-metal contact and cavitation without altering precision wall thickness
• SecureBond™ Adhesion: Micro-etch surface preparation process that strengthens tri-metal structural integrity and reduces the risk of delamination under extreme loads or high-RPM conditions
• Bull's Eye Wall Tolerance: King's advanced quality control maintains bearing wall thickness tolerances to an industry-leading ±0.0001 in., shell to shell
• 1/2 Groove Design: Half-grooved configuration preserves lower shell load capacity for optimal oil distribution and bearing surface area
• 0.020 in. Undersize: Precision ground to 0.020 in. undersize for use with reground crankshafts

Ideal Applications:

• High-load, long-duration racing including circle track, off-road, and offshore applications
• Performance builds using forged steel aftermarket crankshafts
• Engines producing sustained high cylinder pressures and RPM

King Engine Bearings specializes exclusively in engine bearings, allowing them to focus all research and manufacturing expertise on producing the highest quality bearings available in the performance aftermarket. The MB557XPC020 is an ideal choice for serious engine builders demanding race-proven reliability in General Motors 262, 267, 302, 307, 327, and 350 cubic inch small block applications.