Generally, when it comes to valves, a lot of people just rely on what comes with the heads, whether it’s an all-in-one aftermarket solution, or whatever is supplied by your cylinder head porter. But, as we all well know, the core of this hobby is doing different things, and in doing so, you are probably going to find yourself in a situation where the off-the-shelf options won’t work for you. Whether it’s because you have an oddball combination or because you’re just doing something custom.

Understanding this, Ferrea Racing Components offers custom valves to compliment its wide selection of off-the-shelf performance valve options. However, one of the most challenging parts of ordering custom valves is getting the specs exactly right. “We get a lot of requests on how to start the process of custom making valves,” says Ferrea’s Zeke Urrutia. In order to speed up that process for everyone involved, Urrutia offers these tips for the four critical measurements.

Head Diameter

While this one might seem obvious, as it’s the most-often-referred to measurement when discussing valves, correctly measuring it is important. In the case of trying to match an existing valve, using calipers, simply measure the head of the valve from edge to edge. Not a difficult measurement by any means, but a crucial one.

Overall Length

Another crucial, but easy to measure dimension is the valve’s overall length. By simply measuring from the tip of the valvestem to the face of the valve with a set of calipers, you can get the valve’s overall length. One thing to note here, is the more precise you can be here (more digits to the right of the decimal point) the better. You might also need calipers longer than the standard 6-inch variety if you have valves that measure longer than six inches. It sounds obvious, but most people only have a six-inch caliper in their toolbox.

Stem Diameter

Probably the easiest measurement to take and the hardest to mess up is the valve stem diameter. Measuring to the thousandth here is more than enough to get the proper valve stem diameter.

Tip Length

The last of the four major measurements is the tip length. That measurement is from the top of the valve lock groove to the tip of the valve. This can be tricky, as you’ll need to use the blade edge of the caliper to fit within the lock groove for an accurate measurement.

The Ferrea custom valve order form contains every possible measurement on a valve needed to create a design. Luckily, the tech line can help you with most of those, once you know your four major specifications.

With those four measurements, along with your application — be it naturally aspirated, nitrous, turbocharged, or supercharged — and your valve lock groove style and the number of valve lock grooves, you’ll be ahead of the curve when you reach out to Ferrea’s tech line, who will help you complete the custom valve form (found here) and get you into a set of valves that are perfect for your application.