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.

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.

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.

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
(400^OF). This means added protection against localized overheating due to mis-alignment,
detonation, overloading, loss of coolant, etc.

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.

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.
   
   

All
bearing companies solve crankshaft journal wear by supplying oversized
bearings. However, King went two steps further with the development of
Max Flange and Pro Flange. Max Flange reduces endplay by supplying the
flange on the high side of the tolerance to compensate for crankshaft
thrust surface wear; this process is used on all King bearings. Pro
Flange are bearing sets supplied with oversized flanges allowing the
thrust surface to be ground to .010", .020", or .030" undersize.