King SI-Series Main Bearings

4.02 out of 5 stars 85 Customer Reviews

King SI-Series main 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 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.

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King SI-Series Main Bearings MB 557SI

Main Bearings, 1/2 Groove, Standard Size, Bi-metal, Silicon Aluminum, Chevy, Small Block, Set of 5

Part Number: KGB-MB557SI

4.0 out of 5 stars ( 9 )

Estimated Ship Date: Tomorrow

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King SI-Series Main Bearings MB 557SI 040

Main Bearings, 1/2 Groove, .040 in. Crankshaft Undersize, Bi-metal, Silicon Aluminum, Chevy, Small Block, Set of 5

Part Number: KGB-MB557SI040

Not Yet Reviewed

Estimated Ship Date: Tomorrow

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King SI-Series Main Bearings MB5840SI

Main Bearings, King SI-Series Main Bearings, Stock Size, Bi-Metal, Chrysler, Dodge, Sold as a Set of 5

Part Number: KGB-MB5840SI

1.0 out of 5 stars ( 1 )

Estimated Ship Date: Tomorrow

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King SI-Series Main Bearings MB 529SI 030

Main Bearings, 1/2 Groove, .030 in. Crankshaft Undersize, Bi-metal, Silicon Aluminum, Ford, Small Block, Set of 5

Part Number: KGB-MB529SI030

Not Yet Reviewed

Estimated Ship Date: Tomorrow

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King SI-Series Main Bearings MB5840SI0.25

Main Bearings, King SI-Series Main Bearings, .010 in., .25 mm Crankshaft Undersize, Bi-Metal, Chrysler, Dodge, Sold as a Set of 5

Part Number: KGB-MB5840SI025

Not Yet Reviewed

Estimated Ship Date: Tomorrow

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King SI-Series Main Bearings MB 445SI 010

Main Bearings, 1/2 Groove, .010 in. Crankshaft Undersize, Bi-metal, Silicon Aluminum, GM V6, Set of 5

Part Number: KGB-MB445SI010

Not Yet Reviewed

Estimated Ship Date: Tomorrow

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King SI-Series Main Bearings MB 445SI

Main Bearings, 1/2 Groove, Standard Size, Bi-metal, Silicon Aluminum, GM V6, Set of 5

Part Number: KGB-MB445SI

Not Yet Reviewed

Estimated Ship Date: Tomorrow

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King SI-Series Main Bearings MB 459SI0.25

Main Bearings, AM-Series, Alecular Silicon, 0.25mm Crankshaft Undersize, Mitsubishi, 3.0L, Set of 4

Part Number: KGB-MB459SI025

Not Yet Reviewed

Estimated Ship Date: Mar 13, 2026 if ordered today

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Estimated Ship Date: Mar 13, 2026 if ordered today

King SI-Series Main Bearings MB 445SI 020

Main Bearings, 1/2 Groove, .020 in. Crankshaft Undersize, Bi-metal, Silicon Aluminum, GM V6, Set of 5

Part Number: KGB-MB445SI020

5.0 out of 5 stars ( 1 )

Estimated Ship Date: Tomorrow

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Estimated Ship Date: Tomorrow

King SI-Series Main Bearings MB 445SI 001

Main Bearings, 1/2 Groove, .001 in. Crankshaft Undersize, Bi-metal, Silicon Aluminum, GM V6, Set of 5

Part Number: KGB-MB445SI001

Not Yet Reviewed

Estimated Ship Date: Mar 12, 2026 if ordered today

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Estimated Ship Date: Mar 12, 2026 if ordered today

Main Bearings, SI-Series, Silicon Aluminum, 0.50mm. Crankshaft Undersize, Ford, Mazda, 3.0L, Set of 4

Part Number: KGB-MB459SI05

Not Yet Reviewed

Estimated Ship Date: Mar 11, 2026 if ordered today

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Estimated Ship Date: Mar 11, 2026 if ordered today

King SI-Series Main Bearings MB 445SI 040

Main Bearings, 1/2 Groove, .040 in. Crankshaft Undersize, Bi-metal, Silicon Aluminum, GM V6, Set of 5

Part Number: KGB-MB445SI040

Not Yet Reviewed

Estimated Ship Date: Mar 11, 2026 if ordered today

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Estimated Ship Date: Mar 11, 2026 if ordered today

King SI-Series Main Bearings MB 445SI 060

Main Bearings, 1/2 Groove, .060 in. Crankshaft Undersize, Bi-metal, Silicon Aluminum, GM V6, Set of 5

Part Number: KGB-MB445SI060

Not Yet Reviewed

Estimated Ship Date: Mar 11, 2026 if ordered today

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Estimated Ship Date: Mar 11, 2026 if ordered today

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