King MB5503XP 010X XP-Series Main Bearing Set Ford 351 Cleveland 5.8L .010" Undersize

The King MB5503XP 010X is an XP-Series main bearing set designed for the Ford 351 Cleveland small block V8 engine. This set is offered in a .010" undersize fitment, meaning it is designed for use with a crankshaft that has been reground and is now .010" undersize at the main journals. King sells main bearings in complete engine sets for a straightforward, all-in-one rebuild solution.

About King XP-Series Bearings:

XP-Series bearings are King's top-tier offering, engineered for extreme performance and high-load capacity applications. These are Tri-Metal copper-lead bearings built for use with cranks machined with large radii (narrow rod bearing edge), featuring enlarged, chamfered oil holes and 1/2 grooved upper shells (on most applications) to optimize oil flow without sacrificing lower bearing load capacity. The XP-Series is the ideal choice for Circle Track and Endurance Racing where sustained high loads demand maximum durability.

Key Features:

• Application: Ford 351 Cleveland Small Block V8 (5.8L, 16V)
• Series: XP-Series — Extreme Performance Tri-Metal Construction
• Undersize: .010" (for crankshafts reground .010" undersize)
• Material: Tri-Metal copper-lead overlay on high-strength steel backing
• Oil Holes: Enlarged and chamfered for improved oil flow
• Grooving: 1/2 groove design on most upper main shells for optimized rod journal oiling
• Designed for use with aftermarket cranks machined with large radii at journal edges
• Sold as a complete engine set

Understanding Bearing Undersize:

The term "Undersize" refers to a thicker bearing shell designed to compensate for a crankshaft that has been turned down (machined smaller). A .010" undersize bearing is thicker than stock to restore proper oil clearance when the crank journal diameter has been reduced by .010". This is not a measurement of the bearing itself being smaller — it reflects the crankshaft's reduced journal size.

Ideal for Circle Track racing, endurance applications, and any high-load, long-duration performance build where bearing integrity under sustained stress is critical.