Second, a higher rocker ratio helps the valve spring keep the lifter on the cam. This increases the rate of wear and causes other unwanted effects. Why use rocker arm ratios to increase lift instead of just increasing lift at the cam? First, high-lift cams tend to have much sharper radii and larger lifter travel distances. This setup also slightly increases duration, but not by the same ratio. Rocker arms are commonly designed to increase lift at the valve by about 1.3 to 1.6 times the lift at the cam. Most rocker arms are designed to increase the lift of the cam by having a positive ratio. Pretty quickly, engine designers realized that just as you can adjust the fulcrum point of a teeter-totter to get a desired ratio of weight and motion, you can also adjust the fulcrum point of a rocker arm to affect a desired ratio. The valve needs to be pushed down, so the rocker arm works like a teeter-totter to change the upward motion of the pushrod to the downward motion needed to open the valve. This is where the rocker arm comes into the equation. The camshaft controls the valves by pushing up on the lifter, which in turn pushes up on a pushrod. The loss of friction may help things last longer, but it’s not going to measurably add power.īefore we get into the hardcore data, let’s understand what a rocker arm does. That’s just not the case, as there’s a great deal more going on. The resultant loss of friction supposedly makes power. A common misconception is that roller rockers are better than their stock counterparts because they use bearings instead of bushings. Let’s separate the poseurs from the rest of us right away. It’s a common question in our world: Does this automotive widget work as promised? Roller rockers are among the more popular and often misunderstood widgets, and they promise seemingly magical gains with few downsides.ĭo roller rockers really improve performance, save gas and make your teeth whiter? Well, it helps if you know how they work, when they’ll work for you, and when they won’t.