Turning Hemi Rocker Arms Into Works Of Art At Reid Machine

It can be said that the stunningly beautiful rocker arm assemblies manufactured for the Chrysler Hemi platform by Reid Machine are a clear case of a product which has been designed and developed to perform at the highest echelons of racing. It doesn’t hurt that a quick look at the machined contours of the arms shows that just as much care has gone into developing the appearance as has gone into ensuring the performance, and that’s a direct reflection of the mindset of the product designer, bill payer, and chief bottle washer at the company, Darrell Reid. But his path is not a traditional one.

“Most of my serious design work is done at home, after hours,” he says.

“But some of it is done here at the shop from 5 to 8 p.m. I’ll turn on Beethoven, Bach, or Tchaikovsky, and it starts to flow. As long as it keeps going, I’ve walked out of here at midnight. I don’t have a racecar, I don’t own a racecar. I started doing this because I have a passion for solving problems from a mechanical standpoint, and making things work. I really enjoy making stuff. When I got involved in this with Manton to begin with, I was like a kid in a candy shop. It’s challenged me from a mechanical and machining standpoint, from the perspective of making the part.”

In the left photo, we have Reid's 426 Fathead-style rocker system assembly, and on the right we have the 392 assembly typically used in nitro-style racing. Although the 426 engine came after the 392 in terms of development, Reid feels that the 392 actually offers a more robust design. If you notice, the mounting plate for the shafts has the head stud going though it from the very top, which offers rigidity in that area versus the scalloped area found on the 426-style rocker. The stud on the 392 design pulls tight all the way through the stand, and in fact Reid has seen 10,600 rpm on 90-percent nitro and it stays together quite well.

Manufacturing rocker arms from scratch to withstand the levels of horsepower seen by cars like our very own BlownZ06 Corvette, which features a 3,000-plus-horsepower supercharged Hemi, and championship-winning engines which make far more power than ours—like NHRA Alcohol Funny Car—is no small engineering feat. We’d consider Darrell Reid an artist, evidenced by the precision machine paths seen on the surface of these rocker arms.

Recently we had the opportunity to tour his small shop where the magic happens, as it’s just down the road from our California office, and were impressed with the serious jewelry which comes out of this four-person shop.

Form follows function to create impressively manufactured materials.

The Features

What starts off as humble pieces of billet steel bar-stock ends up turning into rigid, lightweight, and extremely durable rocker arm assemblies. Darrell Reid took the time to explain some of the details to us regarding the process, although he didn’t share every detail, citing the all-too-familiar competitive secrets clause—and who can blame him?

As each one of these rocker asemblies is truly developed for its particular application, careful attention is paid to the minute details during the manufacturing process, from initial contact all the way through delivery of the finished product.

One way the company works with its customers to ensure they receive the correct products is to ship each one a mockup assembly prior to delivering the finished product, to ensure valvetrain geometry is correct.

“We send those out and provide our customer with a means of checking the assembly prior to purchasing. That way they know their geometry is correct and we don’t have to send assemblies back and forth. We don’t want them to buy it until they know it’s going to work,” says Reid. “We have found that there are three or four heads that are the same—the Brad, the MBE, the Noonan Super 600 Blackhawk head—those particular heads are close enough to each other that we don’t get out of what we would call an acceptable range.”

However, he says the Muscle Head IV from Alan Johnson—which is, of course, the head used on our Hemi—requires a different configuration due to subtle differences in the design.

“We digitized the valve locations and we saw enough of a difference that we wanted to make a different stand; a unique assembly to that specific head,” he explains.

Reid rocker assemblies are an I-beam design, constructed from solid billet 4340 steel and are heat-treated for longevity. Each rocker offers pushrod oiling through the adjusting screw to ensure pushrod tips stay cool and lubricated. Reid’s secret to success is offering components which are optimized to provide the perfect location for the roller over the valve tip.

Every Reid rocker arm starts as a sawed-off chunk of billet steel bar stock, chosen for its material properties and strength, and then the company’s CNC machines go to work to end up with the finished product. Every piece of these rocker arm systems save for the springs, bronze bushings and the nuts and bolts are made in-house at Reid Machine. Most of the machining operations are performed on one rocker arm at a time, with the exception of some of the finishing work, where they can do four rockers at once. The level of precision machine work that goes into these is simply staggering, and Reid credits the company’s development of their proprietary tooling as the key to this consistency.

The Science

In years past, all of these design tasks would have been incredibly labor-intensive, with many, many hours invested in measuring, checking, testing, and measuring again, before a piece of material was ever touched. But these days, thanks to the advances made with respect to digital measuring, 3D modeling, and other computerized manufacturing techniques, the work is done in a different way. In fact, often the customer will be able to send a digital drawing of the cylinder head configuration so that Reid is able to work his magic right on the screen before ever turning on a machining center. Since many of the Hemi cylinder heads the company works with are manufactured from billet, the digital representation of the cylinder head already exists.

The ability exists for one company or customer to send a digital representation of a product, so another company is able to manufacture a mating part to complement it. “You have an exact representation from the machining model. This is what they are making the part from; they sent me the head, the valve tip locations, the pushrod tubes in the head, and the lifter location, and I was able to build my valvetrain from that,” says Reid. The advantage to this is that the cylinder head manufacturer need not send sensitive data like port locations and cross-sections—they can strip this data from the model before sending it to Reid.

What I’m looking for is the most efficient path of converting radial motion into linear motion.— Darrell Reid, Reid Machine

But none of this happens without an initial concept of what the designer—Darrell Reid himself, in this case—envisions with respect to how the product needs to function and look once the design process is complete. To that end, Darrell shares that he doesn’t sleep much.

“What I’m looking for is the most efficient path of converting radial motion into linear motion; when you look at the valvetrain, the lifter is creating linear motion from the radial rotation of the cam. So then you have the linear motion of the pushrod to the rocker. That linear motion puts into play radial motion of the adjuster, which turns into radial motion of the roller at the top of the valve, then converting it back to linear motion of the valve going up and down. At the same time you’re using the arc of the adjuster and the arc of the roller in the most efficient manner so that we don’t have lost motion,” says Reid.

That lengthy explanation helps to explain Reid’s simple goal: maximizing the efficiency of the radial motion to create linear motion on the valve.

What we see here is an image of Reid generating the model for the actual rocker. Where the image above had a representation of the entire rocker system, in this image, it’s the individual part. “You can see on the right-hand screen how many different levels we’re working with as we’re creating the parts. This shows you how much is involved that component,” Reid explains. There are many items which aren’t shown here, either, and he cited competitive secrets in not showing us all of those steps. Suffice it to say that there’s a lot going on here.

Bring In The Computers

Engine components in particular have benefited from the use of computerized modeling programs, as these programs make it far simpler to develop new products than in years past, where parts had to be machined from scratch and blueprints had to be developed in order to manufacture more than one part consistently. With components that see stress levels like rocker arms down—for thousands and possibly hundreds of thousands or more cycles over their lifetimes—Finite Element Analysis and Mastercam CAD/CAM software has been a lifesaver for manufacturers like Reid Machine, especially when it comes to understanding the stress points in the rocker body.

“As I’m building the rocker, I know that the basic construction—the rib thickness and things of that nature—that doesn’t change, unless we go into a Top Fuel rocker. Once I get the rocker built into its configuration, I’ll move into SolidWorks and do the FEA. We’ll put loads on the roller and loads on the adjuster, and look at it to see what bright spots we get, and then come back and add material or remove material as necessary,” says Reid.

The 426 Fathead spring savers are manufactured for one reason and one reason only—to help combat valvetrain instability. Reid received feedback from several teams, who offered up that the rockers were bouncing off the stands, so they developed these to fit between the rocker and the stand in place of the spring. These provide a solid stop for the rocker, to keep it from moving side to side. They have proven to be a stabilizer, which also has the effect of increasing spring life.

They are also analyzing the rocker’s weight consistently to determine how much weight is over the nose of the rocker. With knowledge of the mass of the component, they can see where the center of gravity of the roller is at any given time with the roller and adjuster included. They also inspect the moment of inertia to visualize where the weight is on the rocker arm.


“The rocker itself may be ‘heavy,’ but it’s the proper distribution of weight that is most critical,” says Reid.

“Think of it as a big guy and a small guy. If the big guy is standing on the valve tip side, he becomes valve weight, which is going to affect the valvespring and the inertia of the valve going down. If it’s a high amount of weight, then the valve wants to loft, and the spring has to work harder—and slows the spring down—in the process of getting the rocker back up,” says Reid.

Weight is removed where possible, and retained where necessary, in the interest of manufacturing a product that will withstand immense spring loads and combustion pressures to function correctly, every time. Many, many hours of research and development have gone into the details of these pieces, from material selection to tooling construction to the choice material used in the shaft bushings and springs.

Since the manufacturing process at Reid Machine is kept under wraps, for the most part, we’re unable to show you how the tooling itself is configured. It’s cost Darrell many sleepless nights to determine the best ways to make the machinery do what he needs it to do in order to manufacture these products, so you’ll just have to take our word for it when we tell you it’s impressive.

(Left) By utilizing four-axis programming and machinery, Reid Machine is able to create rocker arm systems that double as jewelry. (Right) L—R: Marla is the most important cog in the wheel as she keeps the team on the straight and narrow, Patrick, who has been with Reid since graduating high school, shop manager David, and Darrell himself on the right. David and Patrick do the majority of the floor work.

In Conclusion

If you’re looking for the ultimate solution to keep your Hemi valvetrain under control, then you owe it to yourself to check out these beauties. We’ve already tested them to well over 3,000 horsepower in our Radial Vs. The World Corvette, set a record, and won two of the first three races where the car has competed.

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About the author

Jason Reiss

Jason draws on over 15 years of experience in the automotive publishing industry, and collaborates with many of the industry's movers and shakers to create compelling technical articles and high-quality race coverage.
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