It's imperative to make sure that the valvesprings you're using can handle the cam you're using. If the spring binds, or becomes "stacked," you can end up with a lunched cam. So, while you're compressing springs, here are two ways to check for coil bind:

1.800 Installed spring height
-0.500 maximum valve lift
=1.300 Compressed spring height

With the spring at its compressed height, you should have a minimum of 0.060 inch clearance between the coils, measured with a feeler gauge.

You can also compress the spring until it is completely compressed ("solid height"), make a measurement, and subtract this figure from the compressed spring height. For example:

1.300 Compressed spring height
-1.200 Solid height
=0.100 Compressed spring clearance

And as it turns out, 0.100 inch is the minimum clearance you should have. Whatever method you use, this is an easy way to ensure valvetrain longevity.


Shims come in 0.015-, 0.030-, and 0.060-inch sizes. If you're 0.005 short, that's OK; if you're 0.010 short, use a 0.015 shim to come in at 0.005 over.

Taking 0.006 inch off the head surface decreases the chamber volume by 1cc.

If you're not having a valve job done, each valve must go back in its original spot.

Use a spring locator instead of a .060-inch shim. it'll positively locate the spring, and its extra durability will protect the head surface.

COMP Cams Speed-O-Motive
131 W. Lang Ave.
West Covina
CA  91790
Powerhouse Products
3402 Democrat Rd.
TN  38118