Cylinder Head Parts and Functions

When it comes to cylinder head parts and functions, many people do not have adequate information. That is why we wrote this article. It contains details about the role of different parts of a cylinder head. We also included images for the cylinder head components to help you understand them better.

A cylinder head may look simple from outside. However, it is a complex structure containing ports and spaces to hold different components. Here are pictures of cylinder head parts, names, and the functions of each.
 

Cylinder Head Parts List

The cylinder head is made up of many parts, some major and others not so noticeable. They are:

1. Head Gasket

This is the part found between the cylinder head and the engine block. A cylinder head gasket is set with bolts to the top of the engine housing. It is usually made of steel metal. One of the main functions of a cylinder head gasket is to act as a seal between the cylinder head and the engine block. It prevents oil and engine coolant from leaking or mixing. Intake and exhaust gases, too.

Another important cylinder head gasket in cars is to help maintain the pressure of combustion gases. Without the gasket, the two components are likely to fail as a result of loss of pressure. This would, in turn, cause the engine to reduce its performance significantly.

The head gasket life expectancy varies depending on vehicle usage. Heat destroys it quickly. Excessive temperatures are the main cause of a split head gasket and should be avoided. Performance head gaskets are made to withstand harsh conditions and last a long time.

2. Intake and Exhaust Ports

The intake and exhaust ports are part and parcel of the cylinder head. The intake manifold function is to channel air through the passages in the cylinder head and into the combustion chamber.

After the combustion process, the gases produced must be removed. That is the role played by the exhaust. The exhaust ports connect to the exhaust manifold to drive out the gases. This prevents a buildup of internal pressure, which would otherwise result in an explosion.

3. Cylinder Head Valves

In an engine, valves close and open to let in or block the entry of air and fuel into the combustion chamber. Each cylinder in an internal combustion engine has two valves- the intake valve, which is usually bigger and a smaller exhaust valve.

Several components hold and control the working of cylinder head valves. The parts are explained next.

• Valve spring- the valve spring helps keep the valve shut. Depending on the design, a valve spring may comprise one or two different springs, sometimes even three. The triple spring construction is mostly found on performance engines where a high level of reliability is required.
   
• Valve spring retainer- as its name suggests, the spring retainer is the part that helps to maintain the spring position. It mounts on the spring’s top end. The valve spring retainer is usually made from steel.
   
• .Retainer lock- the retainer lock is the part that lies between the spring retainer and the tip of the valve. The pressure or force exerted by the spring helps to hold the lock in place and the components intact.
   
• Valve seal- mounted on the valve stem, and just under the spring, the valve seal prevents cylinder head leaks. It keeps oil from getting into the intake and exhaust passageways and ensures the proper working of these cylinder head parts.
   
• Valve guide- the valve guide simply guides the valve. Valve guides are the metal pieces, usually iron or bronze, that position and allow for free movement of valves. The guides are usually removable parts, pressed into the cylinder head during installation. This makes replacing them during cylinder head refurbishment easy.
   
• Valve seat- this part provides a seat that the valve makes contact with to form a seal. Together with the valve, the cylinder head valve seat prevents combustion gasses from escaping until the valve opens. Seat valves are made from hardened iron alloy and forcefully driven into the cylinder head to create an airtight seam.
   
• Spring seat- some cylinder heads contain a spring seat. The spring seat is usually placed between the spring and the surface of the cylinder head. It protects the head from being damaged by the spring as it compresses and expands. These parts are often found on aluminum heads.
   
• Valve lifter and rocker arm- a valve lifter is the component that opens and closes a valve. It is worked by the camshaft. In an OHC cylinder head, the lifter pushes against the valve directly. The lifter used on a pushrod engine actuates the rocker arm which, in turn, opens the valve. Valve lifters are used on the intake and  exhaust valves.
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4. Cylinder Head Combustion Chamber

The cylinder head parts list cannot be complete without mentioning the combustion chamber. This part can be said to be the core of the engine. The cylinder head combustion chamber is where the air/fuel mixture burns to produce the power to move a vehicle.

Combustion chambers take different shapes and sizes. It depends on the type of engine and vehicle application. The chamber comprises the cylinder head with its ports and valves, the cylinder and cylinder walls, and the piston with its connecting rod.
 

5. Spark plugs

Spark plugs are found in gasoline engines. They convey electricity to the combustion chamber to ignite the air/fuel mixture. The plugs usually mount on the cylinder head, with their tips going right into the combustion chamber. To ensure an airtight seal, the spark plug mounts are usually threaded.
 

6. Fuel injectors

On the cylinder head cover, you will also find fuel injectors. These are basically valves but electronically controlled. In a diesel engine, the injectors push fuel into the combustion chamber directly, with the help of the injection pump. Fuel injectors in a petrol engine use an indirect mechanism for the same function.
 

7. Cylinder Head Camshaft

Overhead camshaft or OVC cylinder heads house the camshaft. On these cylinder head types, the camshaft works the opening and closing of the valves in a timed manner. The crankshaft, which is one of the engine block components, drives the cylinder head camshaft using a belt.
 

8. Other Cylinder Head Parts

The cylinder head cover also contains pathways for coolant to cool the engine, and oil for lubrication purposes. Cylinder head port designs vary, just like the head designs do. Essentially, every type of construction aims at making the part as efficient as possible.

The performance of the cylinder head affects the operation of different cylinder block parts directly. The cylinder head cover gasket, too. When these two parts fail, the engine may not function as required.

A leak of coolant due to cracks or blown head gasket causes the engine to overheat. It can also reduce the compression ratio and make the vehicle to struggle uphill or during acceleration.

Therefore, inspect the head and the head gasket regularly, and fix or replace them if damaged. Also, the cylinder head parts such as valves, springs, and other components.

 

Conclusion

The cylinder head contains most of the mechanical components of an engine. As a result, it determines the engine’s behavior in terms of torque, emissions, cooling, and even acoustics. Armed with the information about the cylinder head parts and functions discussed in this article, you will care for the head better. That, in turn, would mean an engine that performs at its optimum.