King Engine Bearings Main Bearing Set for 1989-1997 Ford Ranger (MB5278AM0.25)

King Engine Bearings Main Bearing Set for 1989-1997 Ford Ranger (MB5278AM0.25)Carrying on a tradition of durability and dependability, KING Bi Metal (aluminum) engine bearings feature 100% lead free aluminum silicon. King has 4 different variations of their aluminum based bearings: (AM Series) K 783 Standard aluminum based material, equivalent to SAE 783, used for low and medium load engines. King AM Series main and rod bearings are recommended for street or marine applications. They have superior embeddability, which provides

Carrying on a tradition of durability and dependability, KING Bi-Metal (aluminum) engine bearings feature 100% lead-free aluminum silicon.

King has 4 different variations of their aluminum based bearings:

(AM-Series) K-783 -Standard aluminum based material, equivalent to SAE-783, used for low and medium load engines.

King AM-Series main and rod bearings are recommended for street or marine applications. They have superior embeddability, which provides greater macro-particle and reduces scratching of the crank journals and tearing or weakening of the Babbitt overlays. The direct replacements feature tolerance control up to +/- .0001—and they're lead-free, making them environmentally friendly and user-safe. Order the King AM-Series rod bearings in the application designed for proper fitment with your vehicle.

(SI-Series) K-788 -Aluminum based material, strengthen by 2.5-3% silicon, for medium load engines or nodular cast iron crankshafts.

King SI-Series main and rod bearings are recommended for OE applications. These replacement bearings are designed for aftermarket gasoline or diesel engine rebuilding—and performance engines with factory crankshafts. The bearings have an improved crankshaft finish for reducing microscopic ferrite peaks on improperly ground or polished nodular cast iron crankshafts. King SI-Series main and rod bearings feature improved oil clearance to reduce wear and increase engine life, which in turn reduces operating noise, vibration, and excess oil flow. Order the bearing set designed for fitment on your make and model.

(SM-Series) K-789 -Aluminum alloy bonding layer. The strongest aluminum based material. The alloy is strengthened by addition of Manganese and Chromium (Mn, Cr), Used for high load applications.

For high load and performance applications, King SM-Series main and rod bearings are the strongest aluminum-based material offered by King. The alloy is strengthened by the addition of manganese and chromium. SM-Series crankshaft main bearings feature a traditional steel-backing, aluminum bonding layer, and the aluminum bearing alloy. They are available for a wide variety of vehicle and engine applications.

(HP-Series) K-787 - King HP-Series rod bearings were developed mainly for drag race applications needing a material harder than the Babbitt top layer. These applications demanded a structure that could withstand high loads for short durations and still offer higher embeddability and compatibility. In response, King developed the HP-Series featuring the Alecular metal structure.

The HP-Series is also suited for many performance applications with nodular cast iron crankshafts, such as street, strip, and some levels of Circle Track racing.

HP-Series bearings are particularly suitable for the following cases:

• When a tri-metal bearing's Babbitt overlay extrudes over the sides, migrates to one end, or is physically removed by the crankshaft
• When the intermediate layer of a tri-metal bearing is exposed, damaging the crank journal and requiring expensive grinding or replacement
• When contaminants enter the oil stream, scratching and damaging the crankshaft journals