June 1, 2023


General For All

What Do Cylinder Heads Do?

You’ve probably seen a lot of ads for cylinder heads, but did you know they’re essential? Cylinder heads are responsible for various aspects of your car’s performance. From intake and exhaust port size to valve spring diameter, cylinder heads are integral to the performance of your engine. Therefore, understanding their functions is essential for maximizing your car’s performance. 

Valve spring diameter

You can change the height of the valve spring in a cylinder head to accommodate the size of the valve. The height of a valve spring is the distance between its spring seat in the head and the bottom of its retainer. This height determines the maximum valve lift spring load and several critical clearances. The easiest way to measure the installed height of a valve spring is with a height mic, which measures the distance from a spring seat to the bottom of the valve spring retainer.

The valve spring diameter is measured from the bottom to the top of the installed spring in the cylinder head. It does not include the spring seat or retainer. For example, a V8 valve spring has an outside diameter of 1.50 inches. In a cylinder head with a 1.5-inch diameter, the valve spring diameter is 1.500 inches. Similarly, an 8mm valve spring is used in the Magnum family of small-block engines. An example would be cylinder heads Victoria TX.

Reverse-flow vs. cross-flow

The reverse-flow cylinder head design is a left-over from the gas engine’s origins. Typical gas inline engines feature manifolds on the same side, which provide a point of attachment for the intake and help it stay warm in cold weather. However, it is no longer the standard design in diesel engines. Instead, specialized companies such as Guenther Heritage Diesel are experimenting with different techniques to improve fuel efficiency and emissions.

Reverse-flow cylinder heads have intake ports on the same side as the exhaust ports. This arrangement allows the fuel and air to mix before exiting the cylinder. This design also helps minimize the effects of reversal flow on the mixture headed to the port. While reverse-flow cylinder heads are less common, they are still helpful for specific applications. For instance, inline industrial engines are not designed to have a broad torque curve, so they will not use them in operational applications where a broad torque curve is needed.

Intake and exhaust ports

A cylinder head’s inlet and exhaust ports are important parts of a cylinder engine. Their placement on the cylinder head affects the flow of air and fuel. Therefore, they should be designed to maximize flow to make the most out of these ports. However, some people find it challenging to design intake and exhaust ports perfectly positioned for maximum flow. Fortunately, there are ways to optimize the flow of these ports.

To maximize airflow through the cylinder head, the intake and exhaust ports should be designed with as few bends as possible. A straight, constant diameter pipe would be ideal. If the ports were connected, there would be no bends. By adjusting the Intake and exhaust ports, you can maximize the flow through the engine head, which will boost performance and efficiency. Intake and exhaust ports can also be shaped to minimize separation.


The various types of cylinder heads produced by manufacturers depend on the configuration of a vehicle’s engine. Therefore, each style has its advantages and disadvantages. Read on to find out more about the different types of cylinder heads and their materials. To understand these different types of cylinder heads, it is helpful to know how cylinder heads are made and which are the most suitable for your car. 

Cylinder heads are made from cast iron, aluminum, or both. Cast iron cylinder heads are the most common and tend to cost less than their aluminum counterparts. However, they weigh more and provide less heat dissipation than aluminum. That’s why most production gasoline engines feature aluminum cylinder heads. On the other hand, cast iron cylinder heads are usually found in diesel engines due to their greater strength. The interior of a cylinder head consists of a series of oil galleries and coolant passages. Some of the heads use a lost-foam casting technique.


If you’re in the business of rebuilding engines, you know how crucial cylinder head testing is. Unfortunately, the conventional methods of testing these parts can miss cracks and fractures, which can lead to serious problems. Cylinder head pressure testing is an effective method for locating such fractures. The testing apparatus comprises a series of individual test plates specifically designed for a particular engine. Each plate includes a planar surface with recesses in a predetermined position corresponding to water conduit outlets inside the cylinder head. The plates are bolted to the engine cylinder head, and water is applied under pressure to determine the fractures.

Once a crack is found, you can use a crack detection system to pinpoint the location of the fracture. The tester also uses an ultraviolet or black light to check for fractures. In addition, it can test cylinder heads prone to cracks and fractures, allowing repair work to be done more efficiently. Cylinder head testing is necessary for any manufacturer or mechanic who wants to ensure their engines are running smoothly.

Valve angle

The angle between the centerline of the valve and the cylinder head is known as the valve angle. Traditional small-block Chevys have a 23-degree valve angle. The angle has remained virtually unchanged since the 1955 introduction of the 265ci small-block Chevy. The angle on modern production engines is more than half that. But what are the benefits of different valve angles? There are a few reasons why the valve angle of your cylinder head matters.

One of the major benefits of modifying your cylinder head is to get the best possible airflow. For example, a sharp angle reduces backward flow. However, intake valve angles are a bit different. A steeper angle decreases backward flow. While different angle values may work in some applications, these angles are specific to the application. Whether upgrading your stock cylinder head or installing a custom-made one, you’ll want to determine the right angle for your application.