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 it measured?
To find the maximum travel of a valve spring, subtract the coil bind height from the Installed Height. (These values will be listed in the valve spring specifications.) Then, subtract 0.050 in. The answer is the maximum valve lift that spring can safely handle.
For example:
|
Installed Height |
Coil Bind Height |
|
1.800" |
1.100" |
1.800" - 1.100" = 0.700"
0.700" - 0.050" = 0.650"
Maximum Valve Lift = 0.650"
How does it 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.
If no valve springs are recommended, you will need to know what to look for.
- Follow this link to lean more about The Basics of Valve Springs.