Understanding the Terminology: Cylinder Head Cover vs. Valve Cover vs. Cam Cover

When exploring the inner workings of an engine, it is important to understand the different components and their specific functions. One common misunderstanding is the difference between a cylinder head cover and a valve cover. Though these terms are sometimes used interchangeably, there are distinct differences based on the engine type and the specific cover's function. Let's break down these terms and provide clarity.

Are a Cylinder Head Cover and a Valve Cover the Same Thing?

Yes, a cylinder head cover and a valve cover often refer to the same component in an engine. This part is typically made of metal or plastic and sits on top of the cylinder head, sealing the area where the valves and camshaft are located. The primary functions of this cover include:

Protecting the internal components Confining oil within the engine Preventing debris from entering the engine

Despite being commonly referred to as a cylinder head cover, this term can be misleading as it does not specifically describe the cover's primary function or what it covers. In fact, many engine covers, especially those designed to reduce noise, may not fall under this exact description.

Overhead Valves (OHV) and the Rocker Arm Cover

When discussing engines with overhead valves (OHV), the official name for the cover is the rocker arm cover. This term is used because, when you remove the cover, you see the rockers, valve spring retainers, and a small part of the valve stems and pushrods. The main parts of the valves are, however, hidden inside the engine.

The label rocker arm cover is more descriptive and accurate, but the general public, often influenced by magazine writers, may use less precise terms. This practice is common and can sometimes lead to confusion. The rocker arm cover is an essential component for maintaining the proper operation of the valve mechanism in an OHV engine.

Overhead Cam (OHC) Engines and Cam Covers

In engines with an overhead cam (OHC) design, the term cylinder head cover is not as accurate. Instead, these engines typically have cam covers, which are more descriptive of the components they cover. When you remove a removable cam cover, the first thing you see are the camshafts.

These covers serve a purpose similar to the rocker arm covers in OHV engines. They protect the camshafts and other internal components while preventing debris from entering the engine. However, the term cylinder head cover in this context is less precise, particularly for OHC engines.

Modern Engine Covers for Noise Reduction

Nowadays, there is a growing trend towards adding additional covers to engines, primarily designed to help reduce noise levels. These covers are different from the traditional cylinder head and cam covers. They are more appropriately labeled as noise reduction covers and serve a unique purpose in the overall engine design.

The term head cover is indeed a misnomer in this context since it does not describe the function effectively. Valve covers and rocker covers are more commonly used terms, especially for those entering the field of engine repair and maintenance. As OHC engines have become more popular, the term cam cover has emerged as the standard.

In conclusion, understanding the terminology of engine components is crucial for both the professional and the enthusiast. Whether you are referring to a cylinder head cover, a valve cover, or a cam cover, it is important to use the most accurate and descriptive term based on the specific engine type and its components.