When you've got valve timing problems, there are so many parts that could be at fault: the rocker arms, valve springs, push rods, lifters, and more. On older engines, valve adjustments were much easier than they are today. You could open up the valve cover and sell all of the valve train components right there for you to tinker with. One of the parts that ends up staring you right in the face is the rocker arm. This can be adjusted to be more or less sensitive to the movements of the camshaft; resulting in either a longer or shorter period where the valve is open. Remember valve lash adjustments should only be made when the cam lobe is not lifting the follower. Unfortunately, sometimes the rockers can break or come loose from the trunnion. This is sometimes the result of a bad trunnion bearing or poor lubrication. If this happens, the valve that it is supposed to open will not open, and engine performance will be hindered. This can be dangerous if gone unchecked for even a brief period of time; so if you hear rattling coming from inside the valve cover then get it looked at immediately.
Rocker arms are responsible for transmitting the rotation of the camshaft to a simple up and down motion for the valve. It does this by "rocking" back and forth over a trunnion or shaft as the cam lobe comes in contact with one side of it. As the cam-actuated side goes up, the roller side goes down and presses the valve. All sorts of rocker arms with different ratios (the ratio between the distance from the center to each of the ends) can be purchased for optimum performance or special tuning. No matter what kind you choose, remember this part is vital to your engine's regular operation.
If you find yourself in the position of replacing your rocker arms, there are some considerations you need to make. First and foremost, you should always have a factory build manual with you. Your engine has a special firing order, and that will be required when you torque the bolts on your new rocker arms. Other than that, the process is rather simple and straightforward. Start by removing the valve cover to expose the valve train. Remove the rocker studs and bolts. Then remove the shaft or trunnion that it pivots on. The arms should come off, and now you can put the new ones on. You can tighten the bolts and studs down by hand initially, but when you fasten them for good you will have to manually crank the engine to TDC with cylinder 1 firing and only torque half of the rockers (which ones are determined by the manufacturer). Then turn 360-degrees to torque the rest. Make sure all new components are lubricated with clean engine oil before installation.
Components as crucial to the normal day-to-day operation of your engine as rocker arms should not be purchased simply because they are the cheapest on the market. That is one way to end up with junk parts. At Car Parts Discount, we carry only premium quality engine internals and timing components. That means no overseas junk will make its way into your engine when you buy rocker arms here.