Rocker arms are the translator between the camshaft and the valves, so their job is very important in the horsepower generation process. This job is very stressful physically on the rocker arm and that means the material it’s made from is critical.
The two most common materials used to make rocker arms are steel and aluminum; the choice will depend on your budget and application for the most part, but each has its own advantage. You need to make sure you have selected the right material for your rocker arms, or you will have some catastrophic valvetrain issues.
Sheldon Miller from T&D Machine Products highlights the advantages of steel and aluminum rocker arms.
“The number one advantage for using steel is longevity. While an aluminum rocker can do the job just fine for most applications, the steel really shines since it can deal with years of abuse. Any aluminum rocker arm will eventually fatigue and fail. This is typically seen on the exhaust side first due to the added pressures the rocker is exposed to while opening against cylinder pressure. For the majority of racers, the aluminum rocker is just fine. The cost of an aluminum rocker arm is less versus the steel due to material cost and machine time.”
The cycle time of a rocker arm plays an important role when you’re looking at purchasing a set. An aluminum rocker arm has a lower cycle time due to the nature of the material.
“We typically will recommend a steel rocker arm for a bracket racer due to the high cycle time the racer will expose it to. In an endurance application like a street car, or if there’s a power-adder, we will recommend a steel rocker at least on the exhaust side. If a customer has an aggressive profile cam a steel rocker is also recommended because it is stiffer, too,” Miller states.
If you want to learn more about rocker arms and what’s best for your application visit the T&D website right here.