COMP Cams Hi-Tech Hydraulic Lifters - Manual (Page 3)

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COMP Cams®
3406 Democrat Rd.
Memphis, TN 38118
Phone: 901.795.2400
Part #COMP4-116
Revised 3/22/12
Toll Free: 1.800.999.0853
www.compcams.com
Section I. Setting pre-load with ADJUSTABLE ROCKER ARMS
Turn the engine in the normal direction of rotation. Start with cylinder number one (1). When the
exhaust valve begins to move, adjust the intake valve to the correct pre-load. To reach zero, take
the pushrod between your finger tips and move it up and down while you tighten the rocker arm.
Once you feel the pushrod has no more vertical slack, you are at zero pre-load. Make sure the
pushrod is in the lifter and the rocker arm seat when making valve adjustments. As stated before,
the recommended setting is .045" or 1 turn of the wrench past zero. Now, you can move on to the
exhaust valve on the same cylinder. Begin by rotating the engine over again until the intake valve
reaches maximum lift and is almost all the way back down. Then set exhaust valve using the same
method as the intake (.045" or 1 turn of the wrench past zero). Continue adjusting the valves on
each cylinder in this manner until all valves are adjusted.
Section II. Setting pre-load with NON-ADJUSTABLE ROCKER ARMS
A different procedure is required to set hydraulic lifter pre-load on engines with nonadjustable
rocker arms. First, install the pushrods and torque all rocker arm bolts down in the proper sequence
and torque specification. Rotate the engine by hand in the normal direction of engine rotation until
both the exhaust and intake valves have opened and closed completely. Allow a couple of minutes
for the lifters to bleed down.
Using the valve cover gasket surface on the head as a reference point, place a mark on the pushrod.
The smaller, more defined the mark, the more accurate the measurement. Be sure the reference
point you choose for the first mark is easily accessible and easy to duplicate. The pushrod will be
marked twice. It must be from the same reference point and angle for the measurement to be
accurate.
Loosen the rocker or rocker shaft bolts. Leave the rockers on the head so that they will support the
pushrods. Be sure the pushrods are standing free in the lifters and do not have any pre-load. Using
the same reference point, place a second mark on the pushrod. Make sure the angle and reference
point are the same as the first mark.
You now have two marks on the pushrod: one with the assembly bolted into place as the engine
will run and the second mark with the lifter unloaded. The distance between these two points will
represent the amount of lifter pre-load. If the pre-load is not within .045" to .060", adjustment is
necessary. The simplest way to accomplish this is by using different length pushrods. When
measuring to find the correct length needed, be sure to include .045" pre-load that the lifter
requires. If the engine uses pedestal mount rockers, shims can be placed under the pedestal to
reduce the pre-load. The stands on shaft mounted rockers can also be shimmed in this manner.
Longer pushrods will be needed for insufficient pre-load.
In most cases, only one intake and one exhaust pushrod will need to be checked. If the valve stem
heights are not equal, then pre-load will have to be checked on each valve. If you do need custom
length pushrods, call CAM HELP® at 1-800-999-0853. COMP Cams® offers a variety of
pushrods in most lengths.