1. How do I calculate the maximum valve lift a valve spring can handle?

Use this simple formula to calculate the maximum valve lift for a specific spring:

Installed Height - Coil Bind - .060” = Maximum Recommended Valve Lift

This formula is a general guideline for calculating maximum valve lift with a safety margin of .060”. Other factors such as rpm will also affect valve spring selection, however this is a good formula to use in most performance applications.

2. Will I have to have my cylinder heads machined when I upgrade my valve springs?

For many applications, COMP Cams has valve springs available which simply drop into place, requiring no additional machining.

Some factory cylinder heads (Chevy Vortec heads are a good example) feature small diameter spring pockets and/or tall valve guides, which can create problems with retainer-to-valve guide clearances or coil bind, even with moderate increases in valve lift. In these cases, machine work may be required in order to ensure sufficient clearance.

COMP Cams® offers many tools to help perform this procedure.

3. How do I check my valve spring installed height?

COMP Cams® recommends the use of a Valve Spring Height Micrometer, which is the quickest, easiest and most accurate way to measure valve spring installed height. The Height Micrometer installs in place of the valve spring. Expanding the tool to seat the valve locks, retainer and valve will permit a measurement that is accurate to within .001” to be read directly from the scale on the tool. This measurement represents the valve spring installed height that is appropriate for your application.

4. What factors should be considered when choosing a valve spring?

The three most common factors that should be considered are installed height, camshaft type, and cylinder head valve spring pocket dimensions. Each consideration is equally critical to choosing the correct valve spring for your application.

To begin, your installed height should always be measured (see question three). This is important because the height at which a valve spring is installed can dramatically increase or decrease its rated coil bind clearance and opened/closed pressures. As this can lead to valve spring or camshaft failure, it is vital that you choose the correct spring for the installed height that your cylinder heads can accommodate.

The next consideration is camshaft type. In short, your valve spring pressure rating must be appropriate to the type of camshaft that you are using. Failure to run the correct pressure for the cam type will almost certainly result in engine damage. See the table below for general spring pressure guidelines based on cam type.

Finally note the physical diameter of the spring. Cylinder heads have pockets that can only accept certain diameter valve springs without machine work. To help circumvent the need for machine work, COMP Cams® offers hundreds of different valve springs, as well as valve spring locators and shim kits to simplify the installation process.

If you have any questions about which valve springs to use, be sure to call our CAM HELP™ line at 1-800-999-0853. Valve Springs Pressures By Camshaft Type

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