King Engine Bearings MB5505SI040 SI-Series Main Bearing Set Ford Undersize - V8 351ci 400ci 040

The King Engine Bearings MB5505SI040 is a complete SI-Series crankshaft main bearing set designed for Ford V8 351ci (5.8L) and 400ci (6.6L) 16-valve engines. This set is machined to a .040 in. (1.00mm) undersize, making it the correct replacement choice for engines with reground or worn crankshaft journals at that undersize specification.

Key Features:

• Bi-Metal Silicon Aluminum Construction: Aluminum-based bearing material strengthened with 2.5–3% silicon for improved hardness and load capacity
• Recommended for medium-load engines and applications with nodular cast iron crankshafts
• Half-groove design for proper oil distribution across the main bearing journals
• SI-Series formula engineered for OE-style replacements requiring reliable, consistent performance
• .040 in. undersize to match reground crankshaft journals — verify crank journal sizing before ordering

King Engine Bearings has been a dedicated bearing manufacturer since 1960, producing precision engine bearings held to tight wall thickness tolerances for consistent fitment and long service life. The SI-Series line is an excellent choice for stock rebuilds and OE replacement applications on these classic Ford big-block engines.