Rocker arms play an important role in an internal combustion engine. They are put under a tremendous amount of stress through every rotation of the engine. In a typical V8 OHV engine, the rocker arm reciprocates millions of times through its life cycle.
They overcome friction wear and valve spring pressure with nothing more than “splash oiling.” In an internal combustion engine, the rocker arms are the link between the camshaft and the valve. As the camshaft lobes raise the lifters and pushrods, the rocker arm is lifted up and in turn pushes down on the valve in a see-saw motion. Many stock rocker arms are made of stamped steel or cast metal and feature a fulcrum pivot that is usually a metal to metal contact design. This has proven to be reliable in stock applications with small camshaft profiles and low valve spring pressures but for the performance enthusiast, this design will just not be sufficient.
With larger … Continue reading
Let’s take a look at the component which can be considered the heart of your engine, the oil pump. Whether it’s a wet sump, dry sump, crank driven, shaft driven, etc. it is responsible for supplying the required oil which no engine can operate without. There are many types available along with different delivery systems as well as some new technology in the works.
We’ll begin with wet sump systems since that is what’s used for the majority of street driven vehicles and many competition engines also. Wet sump designs retain the oil in the oil pan’s sump area. The sump is the lowest part of the pan and it can be located at the rear, front or some even have it placed in the center of the pan depending upon the type of engine and chassis configuration that it has to provide clearance for and still hold enough oil to properly lubricate the engine. The pickup for the pump … Continue reading
Engine bearings, those very important steel and aluminum shells that keep everything spinning as it should, are more complex than ever before. Material designs and compositions have evolved into some serious, load handling pieces compared to the parts of long ago. Let’s take a look at the various aspects pertaining to the bearings for crankshaft main journals and camshafts.
Current bearings fall into two basic construction designs, bimetal and trimetal. Bimetal designs feature a steel backing with a top layer of aluminum alloy. Trimetal bearings have a steel backing like the bimetal but contain a copper lead center layer with various materials being used for the top layer depending upon the usage application of the engine. A bimetal bearing is widely used in most OEM applications because it is a harder material and can last for many thousands of miles to provide a longer service life for the engine, also a bimetal is more cost effective to produce. In regard … Continue reading
The rocker arms in your engine have one simple but very important function, transferring the opening and closing events from the camshaft to your valves. They do so by converting the radial movement of the cam lobe into linear movement at the valve. The amount of lift that is achieved is determined by the ratio of the rocker arm which will dictate the actual distance that the valves travel from the valve seats
You have numerous options to choose from in aftermarket rocker arms for just about any push rod type engine and also overhead cam designs as well. There are stock replacements made from stronger materials, roller tip rockers that maintain the OEM style fulcrum mounting but have a roller tip to reduce friction at the valve stem, stud or pedestal mounted full rollers that utilize a needle bearing or bushing at the fulcrum and also have a roller wheel at the tip and shaft mounted rollers for higher … Continue reading
Let’s take a look at the various aspects of pistons designed for performance and competition engines. If we consider the extreme environment that regular cast replacement pistons operate in with the combustion pressures and high temperatures, it’s quickly apparent that when these values are increased it necessitates using a much more efficient component that can withstand the elevated levels. We can also add to that the much higher and/or sustained RPM’s of the engine that could quickly devastate a normal cast part.
There are two types of pistons, cast and forged, and they are manufactured using pretty much the same method as crankshafts except we’re dealing with aluminum instead of steel. In a cast piece, melted aluminum alloy is poured into a mold which when cooled produces a piston that closely resembles its final shape which requires less machining and is more cost efficient. The forging process involves placing a heated billet of aluminum alloy into dies that use … Continue reading