King Engine Bearings MB5527AM0.25 Crankshaft Main Bearing Set Oversize - 0.25mm

The King Engine Bearings MB5527AM0.25 is a complete crankshaft main bearing set in a 0.25mm oversize dimension, designed for OE replacement on Toyota 4A-FE, 5A-FE, and 7A-FE engines. This set includes 5 pairs of bi-metal aluminum-based bearing shells, making it a direct drop-in solution during engine rebuilds requiring a standard first oversize grind.

Constructed from King's AM-Series bi-metal aluminum material (equivalent to SAE-783), these bearings are ideally suited for passenger car engines operating under low to medium loads. The aluminum base layer delivers excellent embeddability, allowing small macro-particles to be absorbed into the bearing surface rather than scratching crank journals or degrading the overlay — helping protect the crankshaft during break-in and normal operation.

Key Features:

• Bi-Metal Aluminum Construction — SAE-783 equivalent material optimized for low to medium load street and marine engines
• Lead-Free Formula — Environmentally safe composite with no hazardous lead content
• Superior Embeddability — Reduces crankshaft journal wear by absorbing particles that would otherwise cause surface damage
• Bull's Eye Tolerance™ Technology — King's proprietary production process using precise machining, overplating, and computerized wall thickness monitoring for exceptional shell-to-shell consistency
• 0.25mm Oversize — Engineered for use with a 0.25mm (0.010") undergrind crankshaft
• 5-Pair Complete Set — All main bearing positions included
• Tolerance controlled to within ±0.0001" for precise oil clearance

King Engine Bearings has specialized exclusively in engine bearings since 1960, supplying the automotive, marine, aviation, and performance racing industries worldwide. The AM-Series represents King's standard OE-replacement bi-metal line — a proven choice for street rebuilds and engine restorations where consistent quality and reliable protection are essential.