The Overhead Camshaft
When shopping for vehicles, the camshaft is at least one place that you will want to pay attention to. In charge of transferring the motions of an internal combustion engine’s cylinders as well as operating its valves, the camshaft is nothing to ignore. With single and double options, all in contrast to the more modern options that look past the camshaft, it is definitely a bold and exciting choice to make. As such, the following items look at the overhead camshaft to provide a little more information on what it is and what options are available.
What a Camshaft is
A camshaft is the shaft to which a cam is fastened, or which a cam is an integral part of. The camshaft and cam work to produce a rotary motion and transform it into linear motion, or vice versa depending on a situation. In an internal combustion engine, this allows the cylinder movement caused by the combustion to rotate the camshaft and produce a rotating motion, therefore moving the motion from linear, up and down, to rotational.
The overhead camshaft (OHC) is a variation of the original design that places the camshaft within the cylinder heads of an internal combustion engine. This means it is above the combustion chambers and the piston heads, which are the items it interacts with. This allows it to drive the valves in a direct manner, producing better results than if the engine had simply relied on overhead valves. It is also a step-up because it relies on fewer moving parts than a car without the OHC and therefore provides for a lighter engine overall.
Single Overhead Camshaft
There are two types of OHCs: the single OHC and the double OHC. A single overhead camshaft is a single camshaft placed within the head of the cylinder. In the case of an inline engine, this means that there is only one camshaft total, but in the case of a V engine or a flat engine there will need to be two camshafts in the vehicle, as the cylinders are too far apart for one. This design allows the camshaft to operate the valves directly, on its own or through a rocker arm. This makes the engine a little less expensive than a dual overhead camshaft and makes some of the replacements a little easier. This was popular in World War II era plane engines as well as some car designs in the 1980s, such as those of the Volkswagen Group.
Dual Overhead Camshaft
While the single overhead camshaft is useful, the dual overhead camshaft is more efficient, more flexible in terms of design, and allows for better airflow through the engine. This is because each camshaft operates a different valve, on the intake valve and one on the exhaust valve for each cylinder head. This also makes it easier to place the spark plug and has made the DOHC engine the preferable option when it comes to OHC in general, though single remains an option, especially for those trying to avoid the more modern multivalve design that goes past all of the OHC designs.
While the overhead camshaft is not the most important part of the engine by far, it is still an important consideration. Multivalve engines are a thing of the present and lack the interest and complexity of the overhead camshaft cars that are still a part of history and modern vehicles. As such, consider going for one that has an OHC or at least test driving one to see what you think. Just make sure to keep the OHC up to par with regular maintenance, as the extra joy of that engines noise and power is connected to how well the OHC is actually working at any one time.