Engines and Components› Engine Bearings

King /

MB 556XPNC STDX BBC XP Series Main Bearings

$143.90

SKU: KNG-MB-556XPNC-STDX

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Special Order
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$100 Minimum Order
30 Days Return
INSTALL DIFFICULTY
DIY PRO SHOP

Moderate — 2–4 hours

Overview

The King MB 556XPNC STDX is a set of BBC XP Series main bearings designed for high-load, long-duration endurance applications. These bearings feature a Tri-Metal Copper-lead construction with a Hardened Overlay and a special pMaxBlack™ coating. The pMaxKote™ ceramic nano-composite polymer coating enhances wear and seizure resistance.
Show original supplier description
The King MB 556XPNC STDX is a premium set of XP Series main bearings developed by King Bearings for demanding racing applications such as circle track, drag racing, and off-shore use, particularly those involving steel crankshafts subjected to high loads and long duration endurance. These bearings utilize a Tri-Metal Copper-lead construction with a Hardened Overlay, enhanced by King's innovative pMaxBlack™ coating for increased hardness. Further enhancing their performance, the XP Series bearings are topped with the pMaxKote™ ceramic nano-composite polymer coating. This advanced coating significantly improves wear and seizure resistance without altering the bearing's original wall thickness dimensions. The design also incorporates narrower main bearings compared to typical OE specifications, making them suitable for crankshafts with large journal fillet radii. Each bearing is finished with a .001 Oversize for additional clearance.

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

Fitment

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Specifications

BrandKing /
Part NumberKNG-MB-556XPNC-STDX
CategoryEngines and Components
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Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

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