Custom Rockers 101: T&D Walks Us Through Its Killer Rocker Arms

If there’s one thing T&D Machine knows about high-horsepower applications, it’s they demand high-caliber solutions. Take for example, Project Evil, our Fox Mustang powered by a 438 cubic-inch small-block Ford V8 built by KBX Performance. Among a long list of custom parts, Project Evil makes use of a custom billet-steel shaft-rocker set from T&D Machine. The badass small-block Ford is bound for X275 competition, and uses Edelbrock SC1 cylinder heads with outrageous amounts of valve lift and spring pressure.

For this application, using billet-steel rockers was crucial — especially on the exhaust side — due to the amount of cylinder and spring pressure the rockers will see. In short, using billet-steel means a more rugged set of rockers, enabling a much longer lifespan. Now, just because Project Evil runs a set of high-caliber rockers like these, doesn’t mean you should run out to your garage and trash your stock ones yet. In this article, we learn about the benefits custom rockers can offer. What’s more, you’ll learn the process of how they’re made, and if custom rockers are the right selection for your application.

Pictured here are T&D’s steel shaft rocker arms for a GM 6.2-liter LS3 V8. These rockers are built to last and feature a larger, much beefier construction over the factory counterparts.

The Custom Difference

The folks at T&D hear “What makes custom rockers different” a lot. Hot-rodders are always on the hunt for the next go-fast part. So, how exactly can rocker arms help you?

In most situations, custom rockers feature a few benefits over their off-the-shelf counterparts, and a slew of benefits over the factory pieces. The good news is, T&D covers just about every aftermarket and OEM cylinder-head application in the race industry, meaning you probably aren’t going to need any R&D for your application.

The main benefit in a shaft-mount rocker is stability at high-RPM or with an aggressive-profile camshaft,” says Sheldon Miller, head of sales for T&D. “Another benefit to T&D rocker arms is our rockers are internally oiled. This means we actually have engine oil pressure supplied to the bearings themselves. This sends oil directly to the roller tip, making it far superior to the ‘splash method’ of oiling.”

Miller elaborates on the benefits of direct oiling compared to the splash method, as it’s not just the roller tip receiving pressurized  oil. The internal oiling also lubricates the rocker arm’s fulcrum and components. “You gain a lot more life out of the bearing and shaft,” he explains. “We also utilize a fully caged bearing and a larger shaft diameter, which work together to increase longevity.”

T&D ensures every rocker arm set has the correct rocker offset for your application. While this may seem like a complicated measurement, it is a critical parameter for both off-the-shelf and custom applications.

Going Custom — Where Do You Start?

If you’re not an expert when it comes to ordering custom rockers, have no fear. T&D has developed a foundation of rocker arm choices to begin the custom-order process. In addition to the options in the sidebar below, Miller adds, “We can build custom stands and change the offset and ratio of the rocker when required by an individual engine builder.”

T&D's Standard Available Options

  • PN 0720 Spring Oil Hole – This is a 0.040-inch hole drilled in the rocker body to direct some oil straight at the spring to keep it cool, enabling more spring life.
  • PN 0721 Bushed Rocker Option – Used in a lot of desert or off-road applications.
  • PN 0727 Steel Rocker Option – For endurance or severe duty applications.
  • PN 0730 Lightweight Rocker Option – A machining operation to lighten up the nose-weight of the rocker arm. This should only be done when the end user knows the valvetrain is stable and everything else in the valvetrain is light too.
  • PN 0731 Needle Bearing Tip Option – We recommend this in high-load or low-oil environments for better valve-guide life and roll smoother under high-load.

Regardless of whether you are ordering an off-the-shelf shelf set of rocker arms, or something custom-tailored to your specifications, all T&D Machine rockers come with a revised internal oiling system as well as larger shaft and fulcrum bearings. Custom features like an integral spring oiler (left) and durable roller-tip needle bearings that combine high-efficiency with rock-solid durability are available as upgrades.

What Does T&D Need For Your Custom Rockers?

Fortunately for most enthusiasts, even if the need for custom rockers arises, T&D says it’s most likely already created something for a prior application.

Custom rocker sets are typically done when someone has moved the port location, the valves, or on a completely one-off custom head,” Miller details. “The head is no longer ‘normal,’ so we have to design around what’s been altered in it.”

Pictured here are Project Evil’s steel rocker arms. These were custom made for our application, as the 438 cubic-inch small-block Ford will see a ton of boost at the strip. Additionally, they were built with a custom 1.75:1 rocker ratio, spec’d by Jon Bennett at KBX Performance. They feature an extremely stout spring-load to handle the almost-full-inch of lift at the valve.

Miller explains going custom is usually a very complicated process which entails a great deal of effort. The process begins with the need for the customer’s cylinder head and one of each valve.

“Once we obtain the cylinder head, we contact the end user to get all the vital information, such as lift at the valve, pushrod diameter, lifter offset and height, deck height of the block, cam location, desired rocker arm ratio, and so on,” Miller explains.

“All of these parameters have a direct effect on the offset of the rocker, and potentially the length of rockers used. Once we have all of this information, the engineering department begins working its magic. We typically use our rapid prototyping machine and make a prototype stand from what we know is needed. Next, we fit the prototype stand to the head and begin fine-tuning for proper geometry. Once complete, the production-ready stand drawings are sent to the shop to start making the final product,” Sheldon affirms.

The standard aluminium rocker arm (left) features a matte-like finish in its construction. The steel rocker arm's finish (right) features a shinier, polished-like surface in its construction. Both material choices are used in high-performance applications, but each has its own strengths and weaknesses.

T&D’s Method of Research and Development

“Our talented group of engineers develop custom rocker sets based on a variety of factors,” Sheldon said, when asked what research and development goes into creating custom rockers.“For starters, we use the rockers’ capabilities as a foundation — along with the intended environment they will be used in — to determine where to go from there.”

According to Sheldon, power limitations on T&D’s rocker arms aren’t a concern either. “There is really no limit to T&D rockers,” he offers. “With our aluminum rockers, we see more than 1,000 psi open pressure with zero issues. The main thing we have to look at is the application. The life of aluminum rockers comes down to cycle time. For a boat racer or a street application, a steel rocker is much better for longevity. Someone with a very aggressive profile cam or heavy power-adder, such as a supercharger, turbocharger, or nitrous application, will see much more longevity, as a stiffer rocker arm helps all around.”

T&D matches customer rockers with its custom stands, completing the package for your high-caliber valvetrain. By using custom-height stands — as opposed to shims — to achieve the correct stand height, an extra part of the assembly is eliminated. While that may not seem like a big deal, when you are at the track, and thrashing to fix something to make the next round, not having to keep track shims is a huge benefit.

Miller wraps up with a quick note on lead time for enthusiasts who are interested in custom rockers themselves. “Lead times can vary depending on a variety of factors,” he says.“It’s not uncommon for engineering to have more than ten cylinder heads in queue and multiple custom stands that are needed all at one time.”

Sheldon explains that if the enthusiast supplies T&D with all the proper dimensions, the process can typically be faster than if T&D has to blueprint the entirety of the head in-house. “This is why the information we get from the end user or engine builder is so important,” he concludes.

If you’re in the market for a set of badass rockers, regardless of application, the team at T&D Machine Products more than likely has a set to fit your needs. And if by chance they don’t, they can create some that will.

These are the custom T&D Machine billet-steel shaft rockers for Project Evil, prior to installation. Built specifically to not only fit Evil’s Edelbrock SC1 cylinder heads, but with a custom-height stand and revised geometry for the lengthened valves used in the combination.

Article Sources

About the author

Harrison Noble

Living in San Diego for most of his life, Harrison was exposed to a variety of cars at an early age. His passion for anything that is fast, or has a V8, brought him to Power Automedia.
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