Whether you’re rebuilding a daily driver or building a high-performance race engine, your choice of engine bearings can make or break your project. King Engine Bearings has earned a reputation for quality and consistency, offering a broad range of main and conrod bearings for both standard and competition applications. In this post, we’ll explore the history of King, explain the key differences between bearing types and sizes, and help you decide which King bearings suit your next engine build.
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A Brief History of King Engine Bearings
King Engine Bearings dates back to the early 1960s, when precision machining and metallurgical advances began to transform engine reliability. Over the decades, King has grown from a niche OEM supplier into a global brand recognised by enthusiasts, engine builders and OEMs alike.
- Founded by engineers dedicated to improving bearing metallurgy
- Early adoption of tri-metal and bi-metal overlay technologies
- Today’s product line covers everything from classic car restorations to modern race engines
This heritage ensures that every King bearing benefits from six decades of continuous research and refinement.
Main Bearings vs Conrod Bearings: Location and Function
Main Bearings
- Sit between the crankshaft’s main journals and the engine block
- Support the crankshaft under radial loads
- Control oil clearance for reliable lubrication
Conrod Bearings
- Fit between the connecting rods and crank journals
- Handle both radial and some thrust loads as the piston travels
- Require precise oil clearance to avoid both metal-to-metal contact and excessive play
Understanding where each bearing goes and how it functions is crucial when choosing the correct King product for your engine.
Why and When to Replace Engine Bearings
Engine bearings wear out for a few common reasons:
- Oil contamination: Dirt or metal particles cause abrasive wear
- Oil starvation: Insufficient oil flow leads to high temperature and scoring
- Fatigue: Repeated cycles eventually crack bearing materials
Signs you need new bearings include low oil pressure, knocking noises from the crank area, or visible scoring when you strip down the engine. Replacing bearings at the correct service intervals or during a rebuild prevents catastrophic crankshaft damage.
Standard vs Racing Applications
King separates its range into two broad categories:
Standard (Road) Bearings
- Designed for longevity and consistent performance under everyday driving conditions
- Thinner overlays suited to lower RPM and modest horsepower figures
- Typically offered in standard and a light oversize (+0.010 mm)
Racing Bearings
- Feature thicker overlays and advanced metallurgy for extreme temperatures and loads
- Options for multi-thousand-rpm endurance, high-boost forced induction and high-power strikes
- Available in a wider array of oversizes (up to +0.050 mm or more)
Choose standard bearings for reliability in daily-use engines and racing bearings when you’re chasing maximum power, extended high-RPM use or aggressive tuning.
Bearing Sizes: Standard and Oversized
King offers bearings in a range of sizes to match your crankshaft’s journal dimensions:
- Standard size: For fresh or flawlessly machined journals
- Light oversize (+0.010 mm / +0.0004 "): Corrects minor journal wear without removing excess material
- Medium oversize (+0.025 mm / +0.001 "): For journals with moderate wear or multiple corrections
- Large oversize (+0.050 mm / +0.002 "): When journals have been ground heavily or repolished
Why oversize?
- Recover worn journals without excessive block machining
- Ensure correct oil clearance after a crank regrind
- Tailor bearing clearance for specific oil viscosities or performance goals
Always confirm journal dimensions with micrometres and follow King’s clearance chart for your engine’s block and crank combination.
Conclusion
King Engine Bearings blend decades of metallurgical expertise with practical options for everything from daily-driven saloons to multi-hour endurance racers. By understanding the differences between main and conrod bearings, standard and racing applications, and the importance of correct sizing, you’ll make informed choices that safeguard your engine and unlock its potential.