King Engine Bearings CR648SI040 SI-Series Connecting Rod Bearing Set Undersize - 040

The King Engine Bearings CR648SI040 is a bi-metal silicon aluminum connecting rod bearing set designed for engine rebuilds requiring a .040 in. crankshaft undersize. Built using King's SI-Series material specification, these bearings deliver reliable performance and precise fitment for medium-load inline six-cylinder engine applications.

King's SI-Series bearings are engineered from an aluminum-based alloy strengthened with 2.5–3% silicon, making them an ideal lead-free OE replacement solution, particularly well-suited for engines equipped with nodular cast iron crankshafts. The silicon content improves journal surface conditioning, providing enhanced seizure and wear resistance compared to standard aluminum bearings.

Key Features:

• SI-Series bi-metal construction — aluminum base alloy reinforced with 2.5–3% silicon for added strength
• 100% lead-free material — environmentally responsible and user-safe
• .040 in. crankshaft undersize — engineered for reground crankshaft journals
• Improved surface finish — reduces microscopic ferrite peaks on nodular cast iron crankshafts
• Optimized oil clearance — reduces wear, lessens operating noise and vibration, and limits excess oil flow
• Manufactured to King's industry-leading wall thickness tolerance of ±.0001 in. shell-to-shell
• Suitable for OE replacement, street rebuilds, and gasoline or diesel engine applications

King Engine Bearings has specialized exclusively in engine bearings since 1960, applying race-proven engineering standards to every product in their lineup. The CR648SI040 is sold as a complete connecting rod bearing set, ready for direct installation during engine rebuild.