Main Bearing Spacer Set SBC 400 Main to 350 Main

The KING BEARINGS Main Bearing Spacer Set SBC 400 Main to 350 Main (MB5224AM) is a precision-engineered steel spacer kit designed to adapt a 350 Small Block Chevy crankshaft to fit in a 400 block. This specialized component solves a common engine building challenge: matching different main journal diameters when combining blocks and cranks from different displacement variants within the Small Block Chevy family.

The kit provides the necessary spacing to maintain correct main bearing alignment and preload when stepping down from the larger 400 main journals to the smaller 350 specifications. Proper bearing clearance and crush is critical to engine longevity—inadequate spacing can result in bearing spalling, excessive play, or premature failure. These spacers are manufactured from durable steel to withstand combustion pressures and maintain dimensional stability across the engine's thermal cycle. The complete kit eliminates guesswork and ensures that bearing installation meets factory tolerances for reliable performance in both street and performance applications.

This solution is essential for engine builders and restorers working with mixed Small Block Chevy components—whether combining blocks and cranks from different eras, addressing core availability, or optimizing displacement and bore combinations. Experienced builders appreciate the precision fit and the elimination of custom fabrication when executing unconventional small block combinations. The MB5224AM spacer set makes this common build scenario straightforward and cost-effective.

KING BEARINGS is a recognized manufacturer of engine bearings and bearing accessories for automotive and marine applications, known for consistent quality control and precise tolerances. This kit is a trusted choice among engine builders who prioritize correct installation of critical components.