AEM TruTime Adjustable Cam Gear 23830BK User Manual

							ADVANCED ENGINE MANAGEMENT INC. 
2205 126th. St. Unit A 
Hawthorne, CA 90250 
Http://www.aempower.com
 
Instruction part # 10-253 
© 2003 Advanced Engine Management, Inc. 
 
 
 
 
TRU-TIME 
CAM 
GEARS 
 
Mitsubishi Eclipse Turbo 
Part number 23 – 830 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.  
						

							 
 
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. 
 
  
						

							 
 
Figure 1A and 1B 
Read and understand these instructions BEFORE attempting to install this 
product. See reference to diagrams on back page. 
1.  All Tru-Time Cam Gears for Mitsubishi have provisions for the cam angle sensor that is 
mounted behind the intake cam gear on the 1995 to 1996 Mitsubishi Eclipse. The models 
starting with the 1997 model year have the cam angle sensor mounted at the rear of the 
cylinder head. 
2.  The procedure to change the gears is identical to the timing belt replacement procedure 
outlined in the factory service manual.  
3.  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. 
4.  Disconnect the negative battery terminal before starting these procedures. 
 
5. 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. 
 
6. 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. 
  
						

							 
 
Figure 2A and 2B 
7. 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. 
i)  The dowel pins near the center of each 
gear will be at the 12 o’clock position. 
ii)  Each gear will have 2 marks at 180° 
apart. At TDC these marks will line up 
horizontally. 
iii)  The oil pump shaft and crankshaft timing 
marks are lined up with reference marks 
on the front engine cover. 
(1) It is important to examine the oil 
pump pulley as the mark is not very 
easily seen (it may be obscured by 
dirt). The mark is a reverse 
embossed dot with white paint on it. 
(b) Loosen the center bolts on both cam gears. 
i)  These bolts are installed at 68 ft-lbs of 
torque from the factory so do not rely 
solely on the tension of the timing belt to 
hold the cam gears in position. 
ii)  The camshafts have hex flats between 
cylinders 1 and 2. Using an appropriately 
sized wrench, hold the camshaft at the 
hex flats as you loosen the cam gear’s 
center bolt. 
(c) Remove the timing belt from the two cam 
gears. This is an appropriate time to replace 
the timing belt if replacement is due or is 
close to the replacement interval. 
(d) Remove the two OE cam gears from both 
camshafts. 
(e) After removing the belt align the oil pump 
sprocket with the previously identified marks 
on the front of the engine.  
i)  Remove the plug on the rear side of the engine block and insert an 8mm rod into the 
hole to lock the pump shaft in position. 
(1) The oil pump shaft also includes the counter-balance shaft. This shaft needs to 
be locked in place during the installation of the timing belt. 
 
8. Installing the Tru-Time Cam Gears. 
(a) Remove the cam gears from the packaging and lay them down on a flat surface. 
(b) Make sure that the timing marks on both gears are set up at 0° and tighten the bolts. 
i)  If the OE intake cam gear is equipped for a cam angle sensor, remove the trigger 
wheel from the OE cam gear and transfer it to the Tru-Time gear that will be used for 
the Intake side using the screws from the OE gear.  
						

							 
 
Figure 3A, 3B, and 3C  
(c) Install the gears on to the camshafts. Tighten the bolts to the proper factory 
specification (68 ft-lbs). As discussed in the removal section, hold the camshaft at the 
hex flats as you tighten the gears. 
(d) From the exhaust cam remove the bolt that is at the 10 o’clock position and from the 
intake cam remove the bolt from the 2 o’clock position. 
 
9. Installing timing belt 
(a) Install the timing belt on the intake cam. Make 
sure that the gear is at the proper position 
with the pin straight up and the alignment 
marks are horizontal. 
(b) Insert a tie wrap (supplied with kit) into the 
open bolt hole and tie wrap the belt to the 
gear. 
(c) The exhaust cam may be off from proper time 
due to the valve spring acting on the cam 
lobes. Use a wrench to rotate the gear into 
proper time as you install the timing belt. 
Insert a tie wrap into the open bolt hole and 
tie wrap the belt to the gear to prevent the 
belt from slipping off the gear during 
installation. 
(d) Timing belt tensioner 
i)  Try to complete the installation of the 
timing belt without loosening the timing 
belt tensioner pulley. However, if difficulty 
is encountered and loosening the 
tensioner pulley eases the installation of 
the timing belt on to the pulley system 
then the tension on the timing belt will 
have to be reset. 
ii)  From beneath, remove the automatic belt 
tensioner. 
iii) On a vise, compress the tensioner until 
the hole in the shaft aligns with the hole in 
the tensioner body. 
(1) This  procedure should be done over a 
15-minute period to allow the tensioner 
to bleed down. If you compress the 
tensioner down too fast you may 
damage it internally (please see the factory service manual). 
iv)  Once the tensioner has been compressed and the holes are aligned, insert a 
1/16th-
inch pin or nail into the holes to lock the tensioner in place. 
(e) Complete installing the belt on to the lower pulleys. 
i)  Ensure that all the timing marks are in their proper position after the belt is installed. 
Any deviation from these procedures can lead to serious engine damage.  
(f) Install the timing belt tensioner. If you loosened the eccentric idler pulley for the 
tensioner you will have to reset that pulley before you complete the assembly.  
						

							 
 
Figure 4 
10. Resetting the tension pulley 
(a) The following procedures are to be completed if the tensioner pulley was loosened 
during the removal of the timing belt. 
(b) With the automatic tensioner in place, loosen the tension pulley-fixing bolt. 
(c) With a suitable tool rotate the tension-pulley 
counter clockwise and apply 3 ft-lbs to the 
center eccentric while tightening the fixing 
bolt. Do not allow the eccentric to rotate with 
the center bolt as you tighten it (refer to 
factory service manual). 
(d) Measure the protrusion of the auto 
tensioner. It should be 4 ± 2mm, if not 
repeat the pulley adjustment procedures.  
(e) Once adjustments are complete remove the 
tie wraps securing the timing belt to the cam 
gears and re-install the bolts. Tighten the 
adjustment bolts of each cam gear to 15 ft-
lbs. Remove the lock pin for the oil pump 
shaft described step 5e. 
i)  Rotate the crankshaft by hand in the 
normal direction of engine rotation at the 
crankshaft. 
(1) Do this several times and make sure 
you do not feel any resistance to 
rotation.  
(a) With the spark plugs out of the 
engine the crankshaft should 
rotate freely. If resistance is 
encountered check to see that the timing marks on all the pulleys line up 
when the crankshaft is at TDC and/or that the oil pump shaft is not locked. 
(2) Check the timing marks for both the camshaft and crankshaft with each 
revolution and that the oil pump shaft marks line up every third revolution. Failure 
to ensure that engine is in proper time will
 result in engine damage. 
 
11. Assembly of engine components 
(a) Once the timing belt is installed and cam timing verified the assembly of the motor is the 
reverse of the procedures just outlined. 
 
12. Cam timing adjustment procedures 
(a) The performance of an aftermarket cam can be optimized by using the AEM cams 
gears by “degreeing in” the proper cam timing for your particular engine set up. This 
procedure is best carried out on a dynamometer so that quantifiable results can be 
measured.  The advancing or retardation of cam timing will affect the peak power of the 
engine by moving the power band up or down. Usually, advancing the cam gives more 
low-end power and, conversely, retarding the cam timing gives a higher peak rpm and 
power. We must emphasize that this is only a generalization and that you must perform 
dyno/track testing to fully realize the benefit of these sprockets. In the absence of a 
dyno, timed acceleration tests can be performed. (We do NOT
 condone illegal activity  
						

							 
 
on the street and STRONGLY recommend the timed acceleration tests be carried 
out at a racetrack.) The method we use to perform the timed tests is to start at a 
constant engine RPM in second gear (both for manual and automatic transmission) and 
then accelerate to the vehicle redline while recording the time it takes to reach redline. 
We perform this test at least 3 times to establish an average reference point. Notice that 
there is no shifting or tire burning (if you do have a traction problem, use a higher gear) 
in this procedure. Using this procedure will give reliable and repeatable data.
   
(b) As outlined at the preface of these instructions adjustments to the cam timing must be 
done with a very conservative approach. Excessive movement of the cams during 
adjustment increases the likelihood that the pistons and valves will touch. 
(c) All testing should be done on a chassis dynamometer or at the test track. Under no 
circumstance should you resort to testing on public roads. 
(d) For early Mitsubishis equipped with a cam driven distributor. 
i)  Verify that the ignition timing is correct (use a timing light to do this, do not guess). 
The ignition timing must be verified EACH time the cam timing is changed because 
the cam drives the distributor. Any change to the cam timing will affect the 
ignition timing.  
ii)  To change the cam timing, loosen the three retaining bolts (figure 1) in the slotted 
holes in the inner hub. Rotate the cam to the desired position and retighten the three 
retaining bolts to 15-ft. lbs. If the head is milled, then retarding the exhaust cam lobe 
timing must be carried out with extreme care.  You must have at least .060” between 
the piston and the valve. 
(e) After the cam timing change is made, re set your ignition timing
 and go out and try your 
acceleration test or perform dyno testing. You must check your fuel calibration after 
each cam timing change in order to perform an accurate test. The cam timing has a 
profound effect of the air/fuel mixture and if it is not optimized for each cam timing 
setting you will not know if the effect of the change in cam timing is positive or negative.  
(f)  When you have concluded testing, re check the cam bolts for tightness, apply Loctite
® 
“red” to the three retaining bolts
, re install the cam belt cover and know that you 
have installed the best cam timing sprocket(s) available. 
 
 
Caution: Cam adjusting bolts loose.  Tighten before starting engine.
 
 
 
 
 
For Technical Inquiries 
Please E-Mail us at 
[email protected] 
						

							 
 
Reference to diagrams: 
 
Figure 1A 
Diagram showing the arrangement of spark plug wires and top center cover. 
Figure 1B 1.  Drive belt (alternator) 
2.  Drive belt (power steering) 
3.  Tensioner pulley bracket (air conditioner) 
4.  Drive belt (air conditioner) 
5.  Pulley (water pump) 
6.  Pulley (power steering) 
7. Pulley (crankshaft) 
8.  Timing belt cover (upper) 
9.  Timing belt cover (center) 
10.  Timing belt cover (lower) 
11. Timing belt 
12.  Tensioner pulley (timing belt) 
13.  Auto tensioner (timing belt) 
Figure 2A Diagram showing the relationship of the pulleys when cylinder no. 1 is at TDC on compression. 
Figure 2B Diagram showing the location of the plug on the rear side of the engine block. Secondary 
diagram shows the balance shaft in its proper position. 
Figure 3A Diagram showing the proper way to compress the tensioner. 
Figure 3B Diagram showing how the lock-pin is to be inserted into the automatic tensioner. 
Figure 3C Diagram showing how to tension the timing belt during assembly of pulley system.  
Figure 4 A.  6 x 16mm flange bolts 
B.  6 x 18mm flange bolts 
C.  6 x 25mm washer assembled bolts 
D.  6 x 25mm flange bolts 
E.  6 x 45mm flange bolts 
 
Torque Specifications 
A/C idler pulley bracket bolts  20 ft-lbs. 
Alternator adjustment bolt  10 ft-lbs. 
Alternator mounting bolts  17 ft-lbs. 
Automatic tensioner  17 ft-lbs. 
Cam gear adjustment bolts  15 ft-lbs. 
Camshaft pulley bolt  85 ft-lbs. 
Crankshaft pulley bolts  18 ft-lbs. 
Front cover bolts  7.2~8.7 ft-lbs. 
Spark plug  18 ft-lbs. 
Timing belt tension pulley  35 ft-lbs. 
Timing belt tensioner pre-load  2.6 ft-lbs. 
Top center cover bolts  2.2 ft-lbs. 
Water pump pulley nuts  8 ft-lbs.