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  Installed Height??

 


"There wasn't a paper in the box to tell me my installed height."

"Do I use the heights in your catalog for my installed height?"

"How am I supposed to know where to set up my springs?"

These are some of the most common questions and comments we hear on the telephone.  We have designed this page to chase away the clouds of mystery that surround the installed height figure.  The bottom line is that figuring installed height is one of the simplest mathematic calculations an engine builder will ever make.

Installed height is the dimension a valve spring will occupy, when the head is completely assembled - the dimension measured from the bottom of the spring retainer to the spring seat in the cylinder head.

 

In order to properly determine installed height for a given application, two figures must be known.  The first figure is the coil bind, or solid, height of the spring that will be used.  The second figure is is the valve lift (NOT lobe lift) with the current camshaft and rocker arm combination to be used.

To these figures, we must add an acceptable amount of coil bind clearance (the dimension between the spring height at full valve lift and the coil bind height).  We recommend an absolute minimum of .060" be used for this clearance figure.

Now that we have these figures in hand, it is time to do the math and establish a minimum installed height.  In this example, we are going to be using a camshaft/rocker arm combination that will provide .800" valve lift and a K-1000H K-Motion Valve Spring, that coil binds at 1.090".

Coil Bind Height        1.090"

Valve Lift                   .800"

Coil Bind Clearance    .060"

Installed Height        1.950"

In the above example, 1.950" would be the minimum installed height figure.  Please note that this is identified as a MINIMUM installed height.  Operating the engine with a shorter installed height dimension will severely reduce the life of the valve spring and will generally lead to breakage of the spring and the related valve train components.

Let's look at our example from another angle.  You know you have 2.000" installed height and .800" valve lift.  If you use a K-1000H K-Motion Valve Spring, how much coil bind clearance will you have?  In this example, we will be subtracting dimensions, rather than adding them.

Installed Height       2.000"

Valve Lift                  .800"

Coil Bind Height      1.090"

Coil Bind Clearance   .110"

As long as a spring will provide the load figures you are trying to achieve at a taller installed height, we recommend using the additional coil bind clearance to your advantage.  This will generally lead to extended spring life.

Another comment we often hear is, "My valve lift is .750", less .024" valve lash."  We simply allow valve lash, which is not a constant figure, to provide an additional bit of 'cushion' in our coil bind clearance.

We hope these examples will help clear up any misunderstanding about how to determine installed heights and coil bind clearance figures.  If you have any questions about your particular combination, please contact our Technical Department for assistance.

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