Frequently-Asked Questions

What sets King Engine Bearings apart from other bearing manufacturers?

What does the prefix/suffix of your part numbers mean?

part no chart

I ordered a bearing in .010” but the box I received says 0.25?

.010 inch is equivalent to 0.25 mm. See below for the inches to mm size conversion chart.

Metric 0.026 0.25 0.50 0.75 1.00 1.25 1.50
Inches .001 .010 .020 .030 .040 .050 .060

What does the X mean after some of your part numbers?

The X stands for .001” extra clearance. We offer this option on most performance items as STDX, 010X, 020X

Your electronic catalog isn’t working for me. I fill in the information fields and hit search, but nothing comes up.

Our catalog is currently only compatible with Internet Explorer. To see full catalog usage instructions, click here >>.

How can I verify that the engine bearings that I have purchased are genuine King Engine Bearings?

Visit our product authenticity verification page here: www.king-bearings.com/uniqode and enter the code on your box.

What are the top reasons engine bearing’s fail?

1. Metal-to-metal contact (mixed regime of lubrication)

Metal-to-metal contact may result from several factors:

  • Insufficient oil supply (oil starvation)
  • Disruption of the oil film caused by bearing material fatigue
  • Misalignment (e.g. hour glass journal, distorted connecting rod)
  • Poor journal surface finish
  • Foreign particles embedded into the bearing surface
  • Low viscosity (diluted or overheated) oil

Metal-to-metal contact may appear in the following forms:

  • Accelerated wear: the bearing is not overheated (shiny appearance)
  • Wiping: the bearing is heavily worn (overlay is partially removed), there are signs of overheating (blackening), partial melting of the overlay. An example of a wiped bearing is presented on the left part of the picture.
  • Hot Short: severe wear, torn surface, heavy overheating, melted overlay and lining material. An example of a Hot Short bearing is presented in the right part of the picture.

2. Fatigue of the overlay or intermediate layer

Two main causes of bearing fatigue:

a) Wrong selection of engine bearing material for the particular engine. Engine parameters affecting bearing loading:

  • Compression ratio
  • Octane number and fuel type
  • Displacement per cylinder
  • Engine type
  • Aspiration type
  • Bore diameter
  • Piston and conrod weights and rotation speed
  • Bearing dimensions

b) Problems associated with the engine operation:

  • Fuel detonation / advanced ignition
  • Running the engine under high loads (torque) at low rotation speeds for a long period
  • Poor conforming of the bearing back with the housing surface
  • Oil starvation causing load concentration at particular bearing surface points
  • Corrosive action of contaminated oil inducing overlay scoring/cracking ;
  • Geometric misalignments (improperly ground crankshaft, distorted connecting rod, distorted crankcase, distorted (bent) crankshaft) causing localization of bearing loading

Overlay fatigue itself does not cause engine failure. However, running a bearing with fatigued overlay for an extended period may lead to flaking of the overlay and a lowering of the oil film thickness.

The conditions for boundary lubrication (momentary dry contact) occur at low oil film thickness. This leads to excessive wear and localized loading, which may result in lining (intermediate layer) failure.

The fatigue of a copper based lining starts with fatigue of the overlay. The overlay flakes off from the underlying layer, disturbs the oil film, and changes the lubrication regime from hydrodynamic to boundary. The load localizes at the contact area causing the formation of small cracks on the lining surface.

The cracks then propagate throughout the lining thickness, meet the steel back surface and continue to advance along the steel-copper boundary. As a result, parts of the intermediate layer detach (flake) from the steel surface.

The appearance of fatigue in an aluminum based lining is similar to that of a copper based lining. It is also a result of overloading caused by running the engine under high loads (torque) at low rotation speeds for an extended period, localized loading of the bearing due to a misalignment, fuel detonation or other factors.

Fatigue cracks form on the surface and propagate inside the lining, reaching the steel back. The cracks then progress along the bond line between the lining and the steel. Ultimately, pieces of the lining may then separate or flake off from the steel back.

What are the main characteristics of an engine/bearing combination to consider when selecting an appropriate bearing?

  • Maximum specific load applied to the bearing. The bearing load capacity (fatigue strength) should be higher than the maximum specific load. A safety factor of at least 10-15% should be taken into account.
  • Crankshaft material.  Nodular (ductile) cast iron shafts have a rough surface resulting from the cast iron microstructure. Such rough surfaces cause increased wear to the soft overlays of tri-metal bearings when metal-to-metal contact occurs. AlSi bearings are more compatible with nodular cast iron crankshafts. Since tri-metal bearings do not have the surface conditioning properties of AlSi bearings, they are better suited for use with steel crankshafts.
  • Possible misalignments and distortions. Aluminum bearings are more tolerant of misalignments and distortions due to the greater thickness of the bearing layer (~0.010”). Tri-metal bearings with Babbitt overlay (thickness 0.0005” – 0.0008”) are more sensitive to geometric defects.
  • Minimum oil film thickness. The value of this parameter is not always known, but it is important for proper selection of the bearing material. If the minimum oil film thickness is 0.000060” or lower, mixed lubrication regime (momentary dry contact) occurs frequently. Tri-metal bearings with soft thin overlays are less suitable than aluminum-silicon bearings.

What are your latest and greatest engine bearing products you offer today?

  1. King Engine Bearings has developed a unique matrix of exceptionally high strength overlay material with a load capacity of about 17,400 psi (twice as high as conventional tri-metal bearings).
    The bearing, identified by the suffix GP, has a tri-metal structure. Its overlay is composed of two materials (neither is lead). One of them (the base) is hard, but has good seizure resistance. The other component is a solid lubricant. It is distributed throughout the base material, improving its antifriction properties.
    The material has been successfully tested in one of Ron Shaver’s sprint car engines under extreme service conditions (a constant torque up to 500 ft lbs). In order to achieve higher specific loads, the surface of each GP bearing was reduced to under 2/3 of original — and the GP overlay withstood the tests without fatigue.
    In addition to an extremely high load capacity, GP bearings have a superior maximum operating temperature over 500 F. Final pre-production testing is expected to conclude shortly.
  2. King Engine Bearings has also developed a special surface hardening process for lead based overlay high performance tri-metal bearings. This proprietary treatment, combined with a reduced overlay thickness (0.0005″) and increased copper content of the Babbitt alloy have produced a 17% increase in load carrying capacity vs. conventional tri-metal bearings. The bearings’ appearance is distinguished from others by its deep black color, a consequence of the surface hardening process.

What can an engine builder do to help ensure longer bearing life?

  • Eliminate the presence of foreign particles between the bearing back and the housing surface
  • Avoid reversing positions of upper and lower parts
  • Avoid dry start
  • Minimize/eliminate misalignments and distortions
  • Eliminate the presence of abrasive particles on the shaft surface and within oil passages
  • Eliminate out-of–shape grinding of the crankshaft (tapered, barrel shaped, hour glass shaped)
  • Eliminate grinding chatter marks (waviness) and lobing
  • Choose an engine bearing whose material and construction is best suited to the application at hand