New Eagle Specialty Products CRS6125B3D 4340 steel H beam rods are 6.125 inch forged steel units, for Chevy small block
applications including 305, 350 and 400 inch, and LT-1, with 1-piece and 2-piece rear seals. Equipped with 7/16
ARP rod bolts, and rated for engines up to 750 HP, the 6.125 inch long Eagle 4340 steel rods are an economical
component to building a bullet proof lower end.
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Eagle H Beam 4340 Rods
All Eagle H-beam rods are forged from certified 4340 chromoly steel. While a lot of companies make
rods from this material, if you pay close attention, you will notice not all 4340 is the same. For
instance, to be classified as "4340 steel" certain alloying elements must be present in certain percentages.
AISI/SAE specifications call for 1.65% to 2.00% nickel content. While this seems like a small difference,
understand that this is almost an 18% variation. 4340 steel with 1.65% nickel will act a little differently
than 4340 steel with 2.00% nickel content. This is just one of many alloying elements involved in creating
4340 steel. Through extensive material testing, Eagle works closely with the foundry we use to achieve a
much tighter tolerance of all alloying elements to our specific requirements. Along with this, the heat
treatment and tempering process used is vital to producing a stong steel. While exactly what Eagle does
is a closely guarded secret, all of this attention to detail results in a stronger and much more consistent
material. Eagle "4340" steel routinely tests 10-15% stronger than "typical" SAE/AISI spec 4340 steel.
Another important design feature is all Eagle H-beam rods are manufactured from a 2 piece forging. This
is significant because it enhances the strength of the rod cap by orienting the "grain" of the metal with
the direction of stress. The stress exerted on the cap is perpendicular to the stress on the beam.
Forged metal, like wood, has a grain "flow". While wood is stronger in compression and tension when the
stress is applied along the grain, it is weaker when the stress is applied perpendicular to the grain.
The same is true for steel. Although not as severely different as wood, forged steel will show the same
type of result. It might be minor, but several "minor" enhancements combined together result in a major
improvement. Eagle also never uses "cracked cap" type of manufacturing. This is a cheap alternative to
try and produce a more perfect fit between the cap and the beam. The problem is that in order for this
to work, the rod material must be brittle (that's bad), and Eagle would have to make the rod as a single
forging. Instead of resorting to those kind of measures to achieve a "pefect" fit - they just
machine the rod and cap perfectly. So much so that it is difficult to see the parting line at all!
Eagle uses the state-of-the-art Sunnen Krossgrinding system to achieve perfect bore size and consistency
unmatched in the industry. This system is completely computer controlled and produces perfect and
repeatable results every time.