A rocker arm is a valve train component. One end of the rocker arm is raised and lowered by the camshaft, and then the other end creates movement on the internal valve, opening and closing it with the rotation. The leverage of the rocker arm determines the force it can put on the valve and is related to the rocker arm ratio. The rocker arm ratio is the distance from the rocker arm's center of rotation to its end divided by the distance from the center of rotation to the point acted on by the camshaft or pushrod.
The rocker arm can push open either an intake or an exhaust valve. This facilitates fuel and air being taken into the combustion chamber at intake and gases being pushed out during an exhaust stroke. The rocker arm not only changes the direction of the motion of the engine valve, it also changes the amount of motion. The rocker arm increases the amount of motion on the valves.
The weight of a rocker arm is another important consideration for selecting the proper part. A heavier rocker arm requires more energy to move whereas material that is not durable enough may get quickly worn out. Rocker arms today are often made from steel though some are made of heavier metals. Many are made from stamped steel because these rocker arms are a proper weight and are durable.
Stresses and vibrations in your vehicle's engine can affect the performance of your rocker arm. Rocker arms experience deflection under engine stress. This is even more likely when operating a vehicle at a higher speed. When the rocker arm is severely deflected, the engine will perform inefficiently. This leads to worn metal and friction in the valve train. With consistent wear, this can result in engine failure.
Worn or broken rocker arms can be replaced from home. To change the rocker arm, disconnect the negative battery cable. Remove the rocker arm valve cover. Be sure to keep valve train components in order; any parts that will be used again should be installed in the opposite order from which they removed. Next, remove the rocker arm nuts, balls and the rocker arm. Take off the engine push rods.
Once these parts have been removed, you're ready to install the new rocker arm. Clean gasket surfaces and coat bearing surfaces with engine oil supplement. Seat the pushrods in the lifters. Install the rocker arm, balls and nuts. Be sure to replace the removed parts to the same location from which they were removed. Install the rocker arm cover, and then reconnect the negative battery cable.
To replace your rocker arm from home, shop high quality rocker arms from Sears. Look for rocker arm pacers, roller rocker arms, replacement rocker nuts, replacement caps and aluminum and stamped steel rocker arms. Sears carries the best brands in auto repair. Find rocker arms and engine parts from Rock, JEGS, Comp Cams, Rampage, Dorman, Melling, Crown Automotive, Moroso and more! While you're shopping for rocker arms, see internal valves, engine push rods and engine valves.