Page 6 - Along the Way December 2020
P. 6
FORMANCE PUSHROD TECHNOLOGY
BY MIKE MAVRIGIAN
advanced materials and are available in 1: This Trend NZ series pushrod uses a bronze insert that is pressed into the end of the 4130 chrome-moly
wall thicknesses to enhance the goal of pushrod. This allows the pushrod shank to be made from one metal, while a softer metal ensures there will
stability. I’m simply saying that if a 3/8” be no galling at the rocker arm end.
diameter pushrod will easily fit, this is 2: This H-series pushrod is machined from a solid billet of H-13 tool steel, making it exceptionally strong.
preferable to a 5/16”, etc. Don’t be overly 3: V-40 cup pushrods feature self-lubricating tool steel tips. Designed for high-RPM, high-power
concerned about pushrod weight, since valvetrains, combining the strengths of H13 with the self-lubricating properties of tool steel.
the pushrod is on the “slower” side of 4: This is actually a Top Fuel-style pushrod which is made from H13 tol steel. This version has a formed
the valvetrain. When it comes to weight cup-style end to maximize clearance. (courtesy Trend)
savings, it’s more important to consider
the faster side of the system (rockers and
valves).
As noted several times in this article,
pushrods are exposed to forces that
try to make them deflect (bend), which
generates unwanted valvetrain harmonics.
This is because of the eccentric loading
that results from the angular load that is
created as the rocker arm moves through
its arc. Materials and design aside, the
longer the pushrod, the more beneficial
it is to use a larger pushrod diameter (the
theory being that a larger diameter tube
will deflect less than a smaller diameter
tube).
It’s best to consult with the pushrod
maker when ordering custom pushrods.
If we’re speaking in very general terms,
76 JULY-SEPT 2018 engine professional
BY MIKE MAVRIGIAN
advanced materials and are available in 1: This Trend NZ series pushrod uses a bronze insert that is pressed into the end of the 4130 chrome-moly
wall thicknesses to enhance the goal of pushrod. This allows the pushrod shank to be made from one metal, while a softer metal ensures there will
stability. I’m simply saying that if a 3/8” be no galling at the rocker arm end.
diameter pushrod will easily fit, this is 2: This H-series pushrod is machined from a solid billet of H-13 tool steel, making it exceptionally strong.
preferable to a 5/16”, etc. Don’t be overly 3: V-40 cup pushrods feature self-lubricating tool steel tips. Designed for high-RPM, high-power
concerned about pushrod weight, since valvetrains, combining the strengths of H13 with the self-lubricating properties of tool steel.
the pushrod is on the “slower” side of 4: This is actually a Top Fuel-style pushrod which is made from H13 tol steel. This version has a formed
the valvetrain. When it comes to weight cup-style end to maximize clearance. (courtesy Trend)
savings, it’s more important to consider
the faster side of the system (rockers and
valves).
As noted several times in this article,
pushrods are exposed to forces that
try to make them deflect (bend), which
generates unwanted valvetrain harmonics.
This is because of the eccentric loading
that results from the angular load that is
created as the rocker arm moves through
its arc. Materials and design aside, the
longer the pushrod, the more beneficial
it is to use a larger pushrod diameter (the
theory being that a larger diameter tube
will deflect less than a smaller diameter
tube).
It’s best to consult with the pushrod
maker when ordering custom pushrods.
If we’re speaking in very general terms,
76 JULY-SEPT 2018 engine professional
