Yes—a properly selected pushrod upgrade can improve valvetrain stability, durability, and the engine’s ability to follow its intended valve motion. Whether it adds measurable horsepower depends on how well the existing pushrods handle the application.
At Manton, we look at pushrods as part of the entire valvetrain. A hot rod, a diesel rebuild, and a competition engine may need very different pushrods, but the goal is the same: transmit motion accurately and survive the operating conditions.
The benefit might be recovering lift lost to deflection, maintaining control at higher RPM, improving tip wear, or helping expensive surrounding components last longer. A horsepower number alone does not tell the whole story.
Why a straight pushrod can still be inadequate
One common assumption is that a pushrod is doing its job as long as it has not bent permanently. Another is that turning the engine over by hand shows how the valvetrain behaves when it runs.
A running engine adds dynamic loads that a slow inspection cannot reproduce. Valvetrain inertia, vibration, and cylinder pressure opposing exhaust-valve opening all affect the loads the pushrod carries.
A pushrod can deflect under those loads and return to its original shape afterward. That is elastic deflection. A permanently bent pushrod represents a more extreme failure, but excessive elastic deflection can cause problems long before that happens.
The pushrod stores energy as it deflects, then releases it as the load changes. That can alter valve lift, timing, and closing behavior. In severe cases, it can contribute to separation and impact loads within the valvetrain. Looking straight on the workbench does not establish that it remains sufficiently stable in operation.
Will stronger pushrods add horsepower?
Upgraded pushrods are not a guaranteed bolt-on horsepower increase. If the existing pushrods already provide adequate control, changing them may produce little measurable power difference.
But when excessive deflection reduces useful valve lift or disrupts valve motion, an appropriate upgrade can help recover performance the engine combination was intended to deliver. Less effective lift can limit airflow, and restricted airflow can limit power.
There is also a second opportunity: operating range. If improved valvetrain stability allows an engine to maintain cylinder filling at higher RPM, it may support additional horsepower. That requires the rest of the combination to support the speed, including the camshaft, springs, induction system, and rotating assembly. Stiffer pushrods alone do not make an otherwise unsuitable engine safe at higher RPM.
Our approach is to select the pushrod that supports the combination, rather than promise the same power gain for every engine.
What larger pushrods showed us in development
During Gen 3 HEMI development testing with an engine shop, we compared pushrod diameters while retaining the same camshaft and valve springs.
Moving from a 5/16-inch pushrod to an 11/32-inch pushrod moved the onset of valvetrain instability higher in the RPM range. Moving again to 3/8 inch improved the behavior further. That was the largest diameter the cylinder head would accommodate without a major redesign, and it provided the best behavior among the configurations tested.
This is an example from our development experience, rather than a published test with an RPM gain we can quote. Its value is the comparison: changing the pushrod helped the existing camshaft and valve springs operate over a wider stable range.
We have seen a related trend in alcohol HEMI applications. Newer combinations with room for larger pushrods have shown improvements in component service life. Better control of pushrod deflection helps the valve follow the closing side of the cam profile more consistently, reducing disruptive loads as the valve returns to its seat.
These experiences are why we consider available pushrod diameter early in a build.
Stiffness versus weight: rocker ratio matters
Saving valvetrain weight is useful, but choosing a pushrod primarily because it is light can work against the engine’s needs.
The pushrod operates on the lifter side of the rocker arm. A higher rocker ratio increases valve travel relative to pushrod travel, but it also increases the pushrod force needed to overcome a given valve-side load. It can also magnify the valve-motion effect of lost pushrod travel.
That makes pushrod control particularly important in combinations using ratios around 1.8:1, such as LS7 and certain LT applications. An engine with a ratio closer to 1:1, such as some Volkswagen combinations, presents a different balance between weight and stiffness.
Diameter, wall thickness, unsupported length, and material properties all play a role. Increasing diameter can be an effective way to improve bending resistance without simply adding the thickest available wall.
The benefit may be longer component life
Some of the most useful improvements occur around the pushrod.
In our experience, particularly in drag racing, improved pushrod control can help valve springs last longer. Depending on the combination, rocker arms, lifters, bearings, and valve seats can benefit as well. Reducing unwanted deflection and rebound helps reduce the impacts those parts experience.
The pushrod ends deserve just as much attention. Balls and cups act as bearing surfaces. Their shape, material, surface hardness, lubrication, and compatibility with the mating components affect service life.
When upgraded rocker arms or lifters change those interfaces, the pushrod must match them. For example, when a rocker uses a tool-steel cup adjusting screw, we specify a compatible tool-steel ball tip. Matching only the nominal tip size is not enough.
What makes a custom pushrod useful?
Manton’s three-piece custom construction lets us select the center section and ends for their individual jobs. The center carries structural loads, while the tips provide the bearing interfaces. That allows combinations of structural tubing, bearing steels such as 8620, and tool-steel tips suited to the application.
We can also configure length, tip style, diameter, wall thickness, and taper. Customers can specify a nominal length in 0.001-inch increments; our stated finished-length tolerance is ±0.005 inch.
Custom tapers are useful when clearance varies along the pushrod. An engine may allow a large center section but require a smaller diameter near the lifter, near the cylinder head, or at both ends. We can tailor the grind to use the space available.
Different wall thicknesses provide another selection tool. Having room for a larger outside diameter does not automatically mean the engine needs the heaviest wall. The entire assembly’s strength, stiffness, mass, and dynamic behavior matter.
Stocking or custom: which should you choose?
For a stock configuration, a correctly matched stocking pushrod is often the most economical route. Producing common configurations in volume lowers manufacturing cost.
Stocking does not automatically mean one-piece construction. Manton offers both one-piece and three-piece stocking options. Our Series 2 one-piece pushrods use precision-machined ends and a surface-hardening treatment to improve wear resistance while retaining the core properties needed for structural service. Black oxide by itself is not a comparable surface-hardening process.
Custom pushrods make sense when a catalog configuration does not match the engine, or when the build needs a particular combination of materials, tips, length, or taper. They can also solve replacement problems when suitable original parts are difficult to find.
A modified engine deserves particular attention. Changes to the heads, camshaft, lifters, rocker arms, or other dimensions can change the required pushrod specifications. Do not assume that the original length remains correct.
For further information, see Why Manton Stocking Pushrods and Why Manton Custom Pushrods.
Five checks that make the upgrade work
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Confirm clearance throughout the lift cycle. Check from the cam’s base circle through full lift and back. Check multiple cylinders, intake and exhaust positions, and end cylinders. Casting variation and component geometry can make one location tighter than another. Allow the operating clearance recommended for the combination; simply avoiding contact during a static check is not enough.
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Match guide plates to compatible pushrods. Manton Series 2 and Series 4 are intended for guide plate use. An incompatible pushrod surface can wear severely against the plate.
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Confirm both tip interfaces. Verify ball or cup style, size, and material compatibility
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Measure the required length. Account for the specified hydraulic-lifter preload or mechanical lash. Manton offers checking tools to help establish the necessary dimensions.
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Verify the oiling path. Some combinations require oil through the pushrod; others do not. Confirm the requirements of the actual lifters and rocker system, especially when mixing aftermarket parts. An omitted oil passage can prevent a component from receiving lubrication.
A larger pushrod that binds is not an upgrade. Neither is a stronger pushrod with the wrong ends, length, or oiling arrangement.
Choose the pushrod for the whole engine
A well-selected upgrade can offer several benefits at once: more accurate valve motion, better stability, improved wear resistance, and longer component life. The main tradeoff may be purchase price when the replacement retains the required fit, mass, and compatibility. Changing diameter, wall thickness, or construction still requires evaluating the entire combination.
If you are upgrading a stock configuration, browse Manton’s stocking pushrods and confirm that the listed specifications match your engine.
If your engine is modified—or you are unsure what it needs—contact Manton for a pushrod recommendation or call 951-245-6565. Have the engine configuration, spring pressures, target RPM, power adders, available clearance, tip requirements, and measured length ready. We can use that information to help select a pushrod that fits the engine and supports its intended use.