AEM 23-831BK Tru-Time Adjustable Cam Gear User Manual

,!

TRU-TIME

CAM

GEARS

Mitsubishi Lancer Evolution

Part number 23 – 831 series

WARNING:

This installation is not for the mechanically challenged! If you
are not mechanically inclined or do not understand the
procedure please do not attempt the installation. Refer the

installation to a reputable mechanic. It is highly recommended to
purchase the factory service manual to use as a guide along with

these instruction sheets

.

Legal in California ONLY for racing vehicles, which may never be used upon a highway.

ADVANCED ENGINE MANAGEMENT INC.

2205 126

Hawthorne, CA 90250

Http://www.aempower.com

Instruction part # 10-7013

© 2003 Advanced Engine Management, Inc.

th

. St. Unit A

You have just purchased the BEST adjustable cam sprockets available. These AEM billet
aluminum adjustable cam sprockets are CNC machined from billet aluminum and then laser
etched with cam timing marks for adjustment up to ±10° at the cam or ±20° at the crankshaft.
Using the vernier scale on the sprocket hub helps to do the cam timing changes quickly and
accurately. The inner hub is anodized for lasting beauty and resistance to corrosion. The out
gear sector is hard anodized for resistance to wear.

We have found that there are significant power gains to be made by adjusting the cam timing
even with stock cams and compression. Adjustable cam sprockets are usually required in
applications where an aftermarket or reground performance cams are installed or the cylinder
head has been milled 0.005” or more. The use of these cam sprockets allows the extraction of
maximum power from your engine. We have recorded gains of up to 10~15 horsepower due to
cam timing tuning using adjustable cam sprockets.

When an aftermarket or reground cam is installed, the original manufacturer’s cam timing
specifications are no longer accurate. The adjustable cam sprocket allows you to make
necessary adjustments to cam timing to maximize the performance of your engine. This is
accomplished by “degreeing in” the optimum cam timing for a particular engine set up.

The adjustable cam sprocket is especially effective when used with heads that have been
milled. The adjustability of the sprocket allows the accommodation of the changes in cam
timing due to the variation of timing belt length from the bottom sprocket to the top sprocket
when the head is milled. If the head has been milled 0.005” or greater the relationship between
the head and the block is altered by moving the head closer to the crankshaft resulting in
retarded cam timing.

It must be emphasized that the preceding descriptions are generalizations and any
adjustments made must be done with a conservative approach and on a dynamometer or on a
racetrack. We do not condone any illegal activity on the street.

Read and understand these instructions BEFORE attempting to install this
product. See reference to diagrams on back page.

1. The procedure to change the gears is identical to the timing belt replacement procedure
outlined in the factory service manual.

2. Obtain a suitable box or container to hold the hardware that will be removed from the
engine during this installation. This will aid in the prevention of lost nuts and bolts.

3. Disconnect the negative battery terminal before starting these procedures.

4. Removal of cam cover
(a) Remove the top center cover.

i) Clean the area underneath the center cover. This is to ensure that you do not allow

any debris to contaminate the engine internals.

(b) Remove the spark plug wires from the spark plugs but do

not remove the spark plugs at this time. Set the spark plug

wires away from the area of work.
(c) Remove the top cam gear cover.
(d) Remove the cam cover.
(e) Remove the spark plugs.

i) The removal of the spark plugs will make it easier to

rotate the engine by hand. Care should be taken not to
allow any small items to fall into the open spark plug
holes while you continue to install the cam gears. Lay
a rag over the open spark plug holes.

5. Removal of timing belt front covers
(a) Raise the front of the vehicle and

support it using properly rated jack
stands. It is important for safety
reasons to use adequate supporting
equipment to prevent injury or

damage to the vehicle.
(b) Remove the front left wheel.
(c) From underneath vehicle, remove

inner debris shield from inside fender

well.
(d) From the engine compartment,

remove all drive belts (a/c,

alternator/power steering belts), and

the water pump pulley set.
(e) Put a jack underneath the engine for support and remove the front engine mount, the

a/c idler pulley, and remove the front center cover.
(f) From underneath, remove the crankshaft pulley and then remove the front lower cover.

6. Removing the timing belt
(a) Rotate the crankshaft so that the number 1 piston is at TDC on compression. Verify that

the camshafts are in proper timing for this position. Fig 2A.
i) The dowe l pins near the center of each gear will close to the 12 o’clock position.

Figure 1A and 1B