Q: What is valve spring coil bind?

A: Coil bind happens when the valve spring is fully compressed. The coils of the spring contact each other. This stops the valve from opening any further. Coil bind can result in damage to the cam lobe, lifter, pushrod, rocker arm, valve stem, etc.

How is coil bind measured?

To find the maximum travel of a valve spring, subtract the coil bind height from the installed height. Then, subtract 0.050″ to find the max valve lift that spring can safely handle.

See this COMP Cams valve spring example:

Installed HeightCoil Bind Height
  1. 1.800″ – 1.100″ = 0.700″
  2. 0.700″ – 0.050″ = 0.650″
  3. Maximum Valve Lift = 0.650″

How does coil bind affect performance?

Coil bind will damage your engine. Valve springs should be capable of traveling at least .050″ more than the max valve lift of the camshaft. Often, the camshaft manufacturer will list a recommended valve spring. When possible, follow the recommendations of the manufacturer.