If you could single out one particular part of an engine that is most misunderstood, you would likely mention the camshaft. The numbers associated with camshaft design have baffled many a car guy for years, and although once understood, the numbers can still cause some confusion for many. But, what many people don’t even give a second thought to, are the valve springs.
Single springs can be used in higher revving engines, using a performance camshaft with hi
Valve springs are one of the parts of your engine that do require more than just a passing glance. Unfortunately, that rarely happens, and the wrong spring is asked to do a job it wasn’t designed to do. Choosing the correct valve spring begins with knowing the application intended (rpm range, camshaft characteristics, etc.), and selecting all of the valvetrain components to achieve the intended goals of the engine. It does absolutely no good to install a cam capable of building power to 8,000 rpm, if you do not have the correct springs. Improper selection of the valve spring is one of the most common causes of engine failure. Other common causes are the incorrect installation, and improper handling of the valve springs.
An important factor when selecting valve springs, is choosing the correct seat pressure, open pressure, and spring rate for the camshaft being used. In theory, you can gain free horsepower just by choosing the proper springs for your engine. But, how do you choose the right spring?
There are many different kinds of valve springs available, but most come in either a single or a dual design. A single spring is just that, one spring that supports the valve and its movement. A dual spring is made up of two springs, one inside the other. Choosing the right spring pressure is paramount to insure that the valve retracts fast enough, and that your engine doesn’t suffer from valve float. You also don’t want to use a spring with too much pressure, and wipe out the cam.
Dual springs are highly recommended when building higher revving engines with medium to hi
Now, since we’ve mention single and dual spring designs, we need to add another style, the Beehive. A few years ago, Comp Cams introduced the Beehive spring, which was designed to deliver increased valvetrain stability, and be much lighter. This was achieved by utilizing less spring pressure with better valve control. It also reduced the weight of both the spring and retainer. Comp says that the unique Beehive shape handles valvetrain stress more efficiently, which eliminates damaging harmonics, and increases high rpm horsepower and durability. The wire used to make the spring was not round, but rather ovate. This oval/multi-arc shape places the maximum surface area of the wire at the point of highest stress to handle valve train stress more efficiently and allow better heat dissipation for longer life. Because of the design, the valvetrain can handle more rpm, and more aggressive cam profiles. The Beehive spring was—and still is—an amazing breakthrough in design, but would you believe that Comp Cams has even one-upped themselves?
New to the game is Comp’s newly-designed, cone shaped Conical spring. Comp’s Conical valve
At the 2013 SEMA show, they introduced what they are calling the Conical spring. This newly-designed spring is expected to become the new standard in high performance valve spring design. This new spring-design utilizes round wire, and features a diameter and progressive pitch-driven natural frequency. We’re told that this design increases the valvetrain’s rpm limit, and reduces resonance concerns by decreasing dynamic spring oscillations. The result is longer spring life, and the ability to run more aggressive camshafts.
The closer a coil is to the retainer, the farther it has to travel for each lift event, wh
We asked Bradley Brown, an engineer at Comp Cams, why these springs will be better than traditional springs, and he told us, “The Conical springs give all the advantages that we have seen with Beehive springs, but add the next level of spring design. With Beehive springs, we were able to deliver smaller top coil and retainer mass, but still retain the similar main spring characteristics as a standard cylindrical spring. With the Conical spring, we have a smaller diameter at the top of the spring, and a tapering diameter all the way down the spring. This allows us to reduce the mass of not only the top, dead coils and retainer, but also the upper active coils of the spring. It’s worth noting that as you travel from the bottom of the spring to the top, coil motion increases, which also increases the acceleration of each coil as you move up. This added acceleration works just like you would think. If we can reduce the spring’s mass in the area of the component with the highest accelerations, then we can increase the stability of the system. With the conical spring, we have not only reduced the mass of the upper part of the spring and increased dynamic stability, but we have also designed in a very progressive pitch profile, that when matched with the changing diameter profile, creates a natural frequency profile that is very progressive. This means the conical springs are very hard to make resonate. That helps greatly, because if we can keep the spring from resonating, we can utilize higher engines speeds. One of the greatest features is that with new material and processing advancements, we have been able to add quality features, and increase the rate of the spring.”
All that technical stuff sounds good, but to the general enthusiast, are they really necessary? I mean, traditional valve springs have been around for a long time, so why reinvent the wheel? We were told that testing has proven that the conical springs do many things well. First, by reducing the active mass of the spring, like stated before, higher engine rpm are achievable with existing combinations. Secondly, the potential is there for enthusiasts to run more aggressive camshaft profiles with current parts. We hear that some folks have also seen longer spring life, because all of these dynamic gains also translate in the spring being more stable, which helps the spring last longer. The dynamic loads are also reduced so longer life of the rest of the valvetrain parts is also achieved. To quote Bradley, “If you want to go faster or farther, you need these parts.”
“It’s worth noting that as you travel from the bottom of the spring to the top, coil motion increases, which also increases the acceleration of each coil as you move up.” — Bradley Brown
Stuff You Gotta Know
Free Height: is the overall height of the spring in an unloaded condition, like when the spring is sitting on the workbench.
Compressed Height: this is the overall height of the spring in a fully compressed condition.
Installed Height: This is the overall height of the spring when it is installed on the head, and the valve is closed.
Coil Bind: This is the difference between installed height and solid height. The rule of thumb is that the maximum valve lift should never exceed the coil bind, minus 10 percent, or a minimum of .050 inch.
Open Height: the overall height of an installed spring, when the valve is in the fully open position.
Seat/Closed Pressure: the specified load on a spring, when the valve is in a fully closed position, measured in pounds per square inch.
Nose/Open Pressure: the specified load, measured in pounds per square inch, on a spring when the valve is in the fully open position. Note: the spring should be replaced if the pressure is less than 10-percent of the advertised open pressure.
Spring Rate: (not to be confused with Spring Rating). The amount of weight required to compress the spring one inch, rated in pounds per square inch.
Spring Rating: specifies amount of load when the valve is fully closed (Seat Pressure) and fully open (Nose Pressure). This may be a range or a specific number. Example: 80/160.