What does the +0.25mm size mean for these bearings?

The +0.25mm designation means these bearings are slightly larger than standard size. This is typically used when the engine's crankshaft journals have been machined down by 0.25mm to remove wear or damage. Using an undersize bearing ensures the correct oil clearance is maintained.

What is the material of these main bearings?

These bearings are made from a bimetal material that features an aluminum silicon base. This composition is chosen for its good load-carrying capacity and compatibility with crankshafts in engine applications.

Are these bearings sold individually or as a set?

This product is a main bearing set, meaning it includes all the necessary bearings for the main journals of the Chevrolet 121 engine.

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Specifications

Brand: King Engine Bearings
Part #: MB5531SI0.25
UPC: 611500465994

King Engine Bearings Chevrolet 121 (Size +0.25mm) Main Bearing Set

Name: King Engine Bearings Chevrolet 121 (Size +0.25mm) Main Bearing Set
Brand: King Engine Bearings
SKU: king-engine-bearings-king-engine-bearings-chevrolet-121-size-0-25mm-main-bearing-t14-770792
Price: 68.79 USD
Availability: BackOrder

$68.79

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King Engine Bearings Chevrolet 121 (Size +0.25mm) Main Bearing Set. A bimetal aluminum silicon bearing set for your engine rebuild.

Key Features

Fits Chevrolet 121 engines.
This is a +0.25mm undersize main bearing set.
Constructed with a bimetal aluminum silicon base material.

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About this part

Product Details

King Engine Bearings is known for making solid engine bearings, and this Main Bearing Set, part number MB5531SI0.25, is a good example of their work. This set is specifically for Chevrolet 121 engines and comes at a +0.25mm undersize, which is important if you're reconditioning an engine that has already been machined.

These bearings are constructed from a bimetal material with an aluminum silicon base. This type of construction is chosen for its ability to handle the loads and temperatures found in an engine's main bearing journals. When you're rebuilding an engine, getting the right bearing size and material is key to ensuring proper oil clearance and long-term durability.