King Engine Bearings MB4272XP0.25 XP Tri-Metal Performance Main Bearing Set +0.25mm

The King Engine Bearings MB4272XP0.25 is a high-performance crankshaft main bearing set designed for the Holden Alloytec 175 and 190 engines. This set is machined to a +0.25mm (0.010") oversize to accommodate reground crankshafts, making it an essential component for engine rebuilds requiring undersized journal dimensions.

Part of King's XP Tri-Metal Racing Series, this main bearing set features the advanced pMax Black™ tri-metal structure — a unique construction that delivers 24% greater overlay hardness compared to conventional tri-metal race bearings. It is engineered for performance applications using forged steel aftermarket crankshafts operating under sustained high loads and elevated RPM.

Key Features:

• XP Tri-Metal Construction: Enhanced copper-lead intermediate layer with nickel barrier and SecureBond adhesion for superior stability and durability
• pMax Black™ Overlay: Proprietary nano-scaled hardening process producing a 24% harder overlay than standard tri-metal bearings with intermediate layer load capacity rated at 17,000 PSI
• Bull's Eye Tolerance™: Industry-leading wall thickness precision — all shells matched to ±0.0001" for consistent oil clearance and reduced assembly adjustments
• Enlarged, Chamfered Oil Holes: Mains feature improved oil feed geometry for optimized lubrication under racing conditions
• Medium Eccentricity Design: Promotes optimum load distribution and improved oil film retention across the bearing surface
• Narrowed Profile: Mains are narrowed to clear large-radius crankshaft fillets common on performance and aftermarket cranks
• +0.25mm Oversize: Sized for use with crankshafts reground 0.25mm undersize (approximately 0.010" undersize)

Ideal for high-load, long-duration performance applications including circle track, off-road, and motorsport builds. King Engine Bearings has been a specialist in precision engine bearings since 1960, supplying the racing and performance aftermarket with industry-leading quality and the widest range of sizes available.