tech articles on the Tech, Tests & Installs page
springs are one of the most critical and most overlooked
components in your engine. Proper
selection of the valve spring begins with identifying
the application and selecting all of the valve train
components to achieve the engine builders’ goals.
spring is selected to complement the system and must
be matched with the entire valve train in order for
the engine to reach its full potential. It does absolutely
no good to install a cam that will rpm to 8000 if you
do not have the correct springs. Improper selection
of the wrong valve spring is one of the most common
causes of engine failure. Other common causes are the
incorrect installation and improper handling of the
Use only the valve springs that will give the correct
spring pressure with the valve both on the seat and
at maximum lift.
The outside diameter of the recommended valve spring
may require that the spring pocket of the head be machined
to a bigger size.
One of the easiest and sometimes most costly mistakes
made in racing engines is not positively locating the
spring. A valve spring that “dances” around
on the cylinder head or retainer causes harmful harmonics
and excessive wear. A spring that is forced onto a retainer
is likely to fail at that coil. That is why we have
such a large selection of steel and titanium retainers,
hardened steel spring seat cups and I.D. locators to
better match our springs. A spring that is contained
properly at the retainer and the cylinder head will
offer the longest possible service life.
Handle springs with care. Never place in a vise, grab
with pliers or hit them with a hammer. This will damage
the surface of the spring, which will cause a spring
When separating double or triple springs, use only a
durable plastic object that cannot harm the shot-peened
surface of the spring. Never use a tool or hard metal
object like a screwdriver.
3. Valve springs are shipped with a rust preventative
coating that should remain on the spring throughout
engine assembly. Do not clean springs with acidic or
evaporative cleaners. This causes rapid drying and promotes
the formation of rust on the surface, which can cause
catastrophic failures. Even a slight amount of corrosion
can grow to be a problem.
When installing springs, use COMP Cams® Valve Train
Assembly Spray (Part #106) to ease assembly and improve
the life of the spring.
COMP Cams® has matched each set of springs for load
consistency. A variance of + or -10% is acceptable for
When checking the spring loads on a load tester (Part
#5313) measure and note the thickness of the retainer
where the outer spring sits. Assemble the retainer on
the spring and place on the base of the spring checker.
Compress the spring to the desired installed height.
This is the measurement between the top of the spring
(on the bottom side of the retainer where the outer
spring sits) and the bottom of the spring on the base.
* NOTE *
Since the retainer is installed in the spring when checking
the spring loads, make certain that the thickness of
the retainer is not included when calculating the installed
height and is accounted for when compressing the spring.
The spring load checker will show to be higher with
the spring installed at the correct height.
Before installing the spring on the cylinder heads,
check the installed spring height (Diagram A). This
is the distance from the bottom of the retainer to the
surface where the spring rests on the head. The valves,
retainers and valve locks will be used in this step.
First, install the valve in the guide, then install
the retainer and valve locks. Pull the retainer tightly
against the valve locks while holding the valve assembly
Measure the distance between the spring seat and the
outside step of the retainer using your height micrometer
(Part #4928or #4929) or a snap gauge and a pair of calipers.
Repeat this procedure for all the valves and record
your Information. After you have measured all the valves,
find the shortest height. This will become the spring’s
installed height on your heads. If your combination
includes a dual or triple spring assembly, it will be
necessary to allow for the inner steps of the retainer.
Once you have determined the shortest installed height,
it will be necessary to use shims to obtain this height
(±.020” is acceptable) on the remaining
valves. These are available through our catalog or at
any of your local COMP Cams® dealers.
Before removing the retainers, measure the distance
from the bottom of the retainer to the top of the valve
seal (Diagram A). This distance must be greater than
the lift of the valve. If not, the guide must be machined.
This is a very common cause of early camshaft failure.
Once the valve springs have been installed, it is important
to check for coil bind. This means that when the valve
is fully open, there must be a minimum of .060”
clearance between the coils of both the inner and outer
springs. If this clearance does not exist, you must
change either the retainer or the valve to gain more
installed height, or change to a spring that will handle
more lift or machine the spring seat for extra depth.
Always check for clearance between the retainer and
the inside face of the rocker arm. This will be most
evident while the valve is on the seat. Rocker arms
are designed to clear specific spring diameters, so
you should check to see that you have the proper rocker
arm/retainer combination. This situation can also be
the result of improper rocker geometry and may be corrected
with different length pushrods or a different length
To aid in the engine breaking process, spray the springs,
rocker arms and pushrods with COMP Cams® Valve Train
Assembly Spray (Part #106).
In a Spring
It is important for new springs to take a heat-set.
Never abuse or run the engine at high rpm when the springs
are new. Upon initial start-up, limit rpm to 1500 to
2000 until the temperature has reached operating levels.
Shut off the engine and allow the springs to cool to
room temperature. This usually will eliminate early
breakage and prolong spring life. After the spring has
been “broken-in”, it is common for it to
lose a slight amount of pressure. Once this initial
pressure loss occurs, the spring pressure should remain
constant unless the engine is abused and the spring
becomes overstressed. Then the springs must either be
replaced or shimmed to the correct pressure.