COMP Cams Camshaft Installation and Degreeing Procedure - Manual (Page 5)

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COMP Cams®
3406 Democrat Rd.
Memphis, TN 38118
Phone: (901) 795-2400 Fax: (901) 366-1807
www.compcams.com
Part #145
Revised 5/4/12
As mentioned, the proper amount of endplay is between .005” and .010.” This can be checked using a
dial indicator and magnetic base on the front of the engine. To do this, push the cam as far back in the
engine as possible, zero the indicator on the upper timing gear, and then pull the cam as far forward as
it will go. The indicator reading is the amount of endplay in the camshaft.
In Chevrolet engines, the front cover must be in place to check endplay because it is the front stop for a
roller cam. A cam button is used to take up the additional space between the timing gear and the front
cover. These are typically made of Teflon/fiber or steel. The steel buttons have a miniature roller
bearing built in. All types are available from COMP Cams® in various lengths, depending on what
front cover you are using.
The Chevrolet front cover design makes using the dial indicator technique of determining endplay
difficult. Some of the front covers have an access hole with a pipe plug in it to allow a dial indicator
extension to go through the hole and contact the upper timing gear. The stamped covers have no such
provision. An alternate technique that can be used is to gently insert a long screwdriver in one of the
lifter bores and carefully pry the cam back and forth using the sides of the lobe in the bore. Do not use
excessive force to try and move the cam. Estimate how much endplay exists from the movement of the
lobe, and adjust accordingly. If the endplay is too much, install some suitable shim material behind the
cam button and recheck. If it is too small, carefully remove some material from the back of the cam
button, reinstall it in the timing gear, and recheck.
One final note of warning: stamped steel Chevrolet front covers are typically very flexible where the
cam button contacts them. This is detrimental to maintaining a consistent amount of endplay. Washers
are available to weld inside the cover to stiffen it. Also, the water pump fits tightly to some front
covers and can act as a support. For most race type roller cam applications the use of a cast or billet
aluminum front cover is strongly suggested to eliminate any front cover flex-induced change in
endplay. COMP Cams® offers two and three piece billet aluminum timing covers for Big and Small
Block Chevrolet engines.
Setting Solid Lifter Valve Lash
Consult the cam spec card for the correct lash specification. All COMP Cams® spec cards list the
“hot” (operating temperature) lash setting, but it will also work for initial start-up. Refer to step 11 on
how to properly set valve lash.
Setting Hydraulic Lifter Pre-Load
When installing a hydraulic cam, new hydraulic lifters or rocker arms, it is necessary to establish the
proper lifter pre-load. Insufficient pre-load will cause excessive valve train noise. Too much pre-load
will cause the engine to idle rough or have low manifold vacuum. It is critical to engine efficiency and
to the service life of the valve train for the lifters to have the proper amount of pre-load. On any
hydraulic camshaft, the ideal lifter pre-load is .030” plus or minus .010.”
Adjustable Rocker Arms: Follow the procedure in step 11 of the camshaft installation instructions to
set the proper pre-load.