King Engine Bearings MB 509XP 001 Main Bearing Set for Chevy 400ci .001" Undersize

The King Engine Bearings MB 509XP 001 is a precision-engineered main bearing set designed specifically for Chevy 400ci small block engines. This set features .001" undersize bearings for crankshafts that have been machined down to restore proper clearances.

XP-Series Performance Technology:

King XP-Series bearings represent the pinnacle of bearing technology for extreme performance applications. These tri-metal copper-lead bearings are engineered for high-load capacity endurance racing, circle track competition, and demanding street/strip use. The advanced tri-metal construction provides superior fatigue resistance and load-carrying capability compared to bi-metal designs.

Key Features:

• Tri-metal copper-lead construction for maximum load capacity and durability
• Enlarged, chamfered oil holes designed for aftermarket crankshafts with large fillet radii
• 1/2 groove design on main bearings for optimized lower bearing load capacity
• High-strength steel backing for dimensional stability under extreme conditions
• .001" undersize thickness for use with turned crankshafts
• Complete engine set includes all main bearings required for installation

Applications:

Ideal for high-load, extended-duration applications including circle track racing, endurance competition, road racing, and high-performance street engines. Compatible with blown, turbocharged, nitrous oxide, and alcohol-fueled Chevy 400ci engines using aftermarket or machined crankshafts.

Important Note: The term "undersize" refers to the crankshaft journal diameter, not the bearing thickness. Undersize bearings are actually thicker than standard to compensate for material removed during crankshaft machining and restore proper oil clearances.