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King OEM Replacement Main Bearing Set ROMEO 4.6 Blocks

King OEM Replacement Main Bearing Set ROMEO 4.6 Blocks

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Our Price: $56.79

Availability:: Usually Ships in 1 to 2 Days
Product Code: KNGMB5353SI

Bearing Sizes

King OEM Replacement 4.6 and 5.4 Bearings are a great choice for any Modular rebuild. Sold in sets of 8.

Tri-metal vs. Bi-metal Bearings

Traditional rod and main bearing construction is based upon a three layer configuration composed of a steel backing, a copper-lead layer and a very thin overlay of babbitt material only .0005" - .0008" thick.

King’s bearing uses just two layers, a high strength steel backing plus a bonded layer of "Alecular" bearing material .012" - .015" thick.

Alecular material is used exclusively by King. It is an alloy of aluminum, tin, copper and several other elements. Because it is an alloy, it maintains its properties throughout its entire depth, delivering consistent and reliable performance.

Benefit No.1 - Particle Embedability

More than half of engine bearing failures are caused by metallic particles which scratch crank journals and tear or weaken thin babbitt overlays such as in the tri-metal bearing.

Since King’s Alecular bearing layer is much thicker than the babbitt overlay (.015" vs. .0008"), it provides eighteen (18) times more embedability than a tri-metal bearing to catch and hold particles so they don’t scratch the crank journals. This is especially true for particles over .0004" in diameter which cause most of the damage.

Benefit No. 2 - Conformability

The much thicker layer of Alecular bearing material (.015" vs. .0008") allows the bearing to conform to problems such as metal to metal contact when there is mis-alignment present or the connecting rods stretch. Greater conformability means fewer bearing failures.

Benefit No. 3 - Temperature Resistance

The Alecular material’s melting/fatigue point is over 11000 F, almost three times that of the thin babbitt overlay in a tri-metal bearing (400OF). This means added protection against localized overheating due to mis-alignment, detonation, overloading, loss of coolant, etc.

Benefit No. 4 - High Load Capacity

Alecular bearings successfully withstand the stresses of blown, nitro-methane burning Top Fuel dragsters generating 5,000 hp at 8,000 rpm and in 700 hp circle track engines running for extended periods of time. The same metallurgical alloy is used in King’s street bearings that is used in King’s High Performance bearings, so the regular bearing user gets the advantage of the alloy developed and used in race engines.

Benefit No. 5 - Control of Wall Tolerance

Bearing -to- journal clearances on main and connecting rod bearings can be affected by several variables, all of which the engine builder must try to control. King has removed concerns about inconsistent shell to shell bearing wall thickness by the use of statistical control methods to keep wall thickness to very limited variation.

Other manufacturers produce bearings whose wall thickness at the crown can vary by up to + .00025". King bearings are produced using "Bull's Eye" specs which set a higher standard of controlling the wall thickness, permitting no more than + .00010" variation of the desired thickness.

The benefits of tight control of wall thickness tolerance are:

  1. Improved consistency of bearing to journal clearance. No more trying different bearings within a set to get the "right" fit.
  2. Superior eccentricity and crush relief values for a better oil "wedge" and less journal wear.
  3. Less taper across the bearing face, meaning superior wall stability, a more parallel wall and better oil film development.
  4. Crankshaft grinder does not need to grind cranks "fat" or "thin" to compensate for bearing variations.
  • Introducing the newest generation of KING’s

  • Alecular bearing technology…


  • Preferred OE Material

  • Versatile ~ Tough ~ Durable

  • SI Bearings WORK…
  • Wear resistance - the silicon particles help round off high spots on the crank surface during engine operation, which reduces friction & related wear.

  • Excellent control of wall variance - because the bearings are unplated, wall variances are reduced by as much as 40% less than tri-metal (over-plated copper lead) bearings.

  • Fatigue strengths dramatically improved - KING’s SI bearings easily exceed maximum peak load capacity for car and light duty applications.

  • Improved oil clearance tolerances - because of reduced wear, SI bearings make it possible to maintain OEM clearances over the life of the engine, which in turn reduces operating noise, vibration, and excess oil flow

  • O.E. preferred material - most O.E. engines today use and take advantage of all these benefits.

  • SI Bearings LAST…

  • Outstanding service life - exceeds OEM engine durability of 150,000 miles

  • Superior temperature threshold - the melting point/flaking point of the silicon bi-metal SI bearings is significantly superior to the older tri-metal design (1,100° vs. 400°). This enables KING Engine Bearings to hold up under tough overheating conditions.

  • Exceptional corrosion resistance – defends against corrosion caused by unleaded fuels and moisture.

  • Minimized debris embedment – because SI bearings are unplated and bored, hard-particle debris is instantly flushed through the bearing and filtered out of engine rather than scoring the crankshaft and causing long term damage.

Average Customer Review: Average Customer Review: 5 of 5 5 of 5 Total Reviews: 2 Write a review.

  0 of 0 people found the following review helpful:
5 of 5 July 3, 2019
Reviewer: Michael Mora from San Antonio, TX United States  

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  0 of 0 people found the following review helpful:
5 of 5 King main bearings October 24, 2012
Reviewer: wayne light from nemo, TX United States  
The bearings are definitely slightly larger, helping to increase oil pressure, and after removing a old set on a different engine, they do polish the journals.  Great service from Modmax racing as always.

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