sum-14917400_xl Summit Racing pushrods HDR

(Image/Summit Racing)

Pushrods take a lot of flak.

“OHC” this, and “primitive” that.

Pushrods don’t live an easy life either. They get covered up, never to see the light of day, and bumped around by cam lobes from one side and smacked back by rockers and springs on the other. It would seem like a thankless job, but a good engine builder appreciates them plenty.

The Consequences of Pushrod Deflection


(Image/Grumpy’s Performance Garage)

When a pushrod deflects, several bad things happen, including:

  • Loss of valve lift.
  • Loss of valvetrain stability. The valve is no longer opening and closing at the rate the lobe designer predicts.
  • Slack in the system means the components start banging against each other and breaking.
  • When valves are bouncing off the seats, they’re not sealing and power is lost.

And remember, it’s not just 500, 800 or 1,300 pounds of open spring pressure that’s causing the deflection.

Inertial loads from heavy valves, springs, retainers, rockers, and the lifter can create more than 5,000 lbs. of force. Think about an entire SUV balancing on top of a seven-inch tube thinner than your pinky. That pushrod is moving around more than a pogo stick in a hula contest.

So how strong does a pushrod need to be? The short answer is: Use the biggest/thickest one that fits.

What about weight? The pushrod moves a short distance compared to the valve, spring, and retainer due to rocker ratio. The weight is much less in comparison too. Because of this, the added strength more than offsets the increase in mass.

Summit Racing HDR Premium Pushrods

Summit HDR Pushrods SKU and spec sheet

Enter the Summit Racing HDR premium seamless chromoly thick-wall pushrods.

These pushrods are 100-percent made in the USA, and come standard with 210-degree ball ends for more rocker clearance at max lift. They are available in common LS, SB Chevy, BB Chevy, and SB Ford Windsor lengths.

How strong are they?

Summit Racing used FEA (Finite Element Analysis) in the initial testing. They could have compared them to thin-wall welded-ball factory pushrods, but who in their right might would use those? The following results are based on improvements over typical .080-wall aftermarket pushrods.

  • The 5/16 x .105 wall pushrods have 25-percent less deflection.
  • The Pro LS 11/32 x .120 are .030 larger in diameter, yet fit in place of the factory 5/16. They’re also available in .025 increments to fine tune hydraulic lifter preload. They have 28-percent less deflection than a typical 5/16 .080 wall chromoly pushrod.
  • The 3/8 x .135 pushrods commonly used in big blocks has 20-percent less deflection.

So the bottom line? Summit HDR pushrods are some of the best horsepower-per-dollar components available for your engine.

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Author: Brian Nutter

After a stint in the U.S. Air Force, Brian Nutter studied at the Houston, TX-based School of Automotive Machinists in 1997. The early part of his automotive career included working for engine builders Scott Shafiroff and C.J. Batten, followed by several years developing performance pistons at Wiseco Piston Co. Today, Brian develops performance parts for Summit Racing Equipment and is a regular OnAllCylinders contributor. For fun, he runs his 427-powered C5 Z06 in ECTA land-speed racing, at OPTIMA® street car events, and at a mix of autocross, drag racing, and track days.