AEM TruTime Adjustable Cam Gear 23850BK User Manual

							ADVANCED ENGINE MANAGEMENT INC. 
2205 126th. St. Unit A Hawthorne CA 90250 
Phone: (310) 484-2322 Fax: (310) 484-0152 
Http://www.aempower.com 
Instruction Part Number: 10-254 
© 1998 Advanced Engine Management, Inc. 
 
 
 
 
TRU-TIME 
CAM 
GEARS 
 
1993 – 1997 Dodge Neon 
Part number 23 – 850 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 
Inc. 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 perform 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 aftermarket or reground cams are installed, the original manufacturer’s cam 
timing specifications are no longer accurate. These adjustable cam sprockets allow 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.
1) It is important that the installer familiarize themselves 
with the procedures before starting the installation. This 
procedure requires some very specialized tools, which 
cannot be substituted with any substandard equipment. 
It is important to have a factory service manual 
available for reference while undertaking this 
installation. This procedure is best accomplished using 
a lift. If a suitable lift is not available, for safety reasons, 
use appropriately rated jackstands. 
2) Disconnect the negative battery cable. 
3) With the front of the vehicle raised, drain the coolant 
from the radiator. The drain plug for the radiator is 
located just to the right of the lower radiator hose (when 
viewed from underneath). Make sure to collect all the 
coolant in a clean container so that it can be re-used. 
a) Disconnect the upper radiator hose and remove 
from the area of work. 
b) Disconnect the coolant line located to the right of 
the radiator hose and position it away from the area 
of work. 
4) Remove all the accessory drive belts. 
See Timing Belt System 
Diagram 
a) Alternator drive belt 
b) Air conditioning and power steering pump belt. 
5) Remove the right front wheel. 
a) Remove the right inner splash shield and the right 
engine-mount bolt access plug. 
See Figure 1 
6) Position a jack underneath engine for support. 
a) Disconnect and remove the purge solenoid valve 
from the right front engine mount. Mark the vacuum 
lines before you remove the valve so that they can 
returned to their original positions. 
b) Remove the two engine mount to frame rail bolts 
on either side of the engine mount.
 See Figure 2 
c) From the wheel well loosen the engine mount 
through bolt. 
d) Jack the engine up until the engine mount clears 
the frame rail and then remove the engine mount 
through bolt. 
7) Remove the power steering pump. This will allow you to 
move the power steering hoses from the front of the 
engine. Try not to disconnect any hoses to prevent 
leakage. If any hoses are disconnected, any o-rings at 
the banjo connections at the top of the pump will need to be replaced. You will also need to prevent any 
contamination of the power steering pump. 
See Figures 3&4 
a) Remove two bolts at the back of the rear bracket 
and loosen one bolt on the front bracket. 
b) Lift the pump up to clear the engine and lay the 
pump on the cam cover. 
8) Remove the front bracket plate. 
See Figure 7 
a) Remove the bolts on the front bracket plate and lift 
the bracket out of the engine compartment. The 
bolts for the front bracket plate are quite long so lift 
the engine as needed to obtain the necessary 
clearance but be careful that other engine 
components are not damaged in any way resulting 
from jacking the motor too high. 
9) Remove the front crankshaft pulley. 
See Figure 5 
a) The stock pulley is an assembled component. In 
most cases a weld gap is evident on the area 
where the Poly-V alternator belt rides. This is the 
normal appearance of the pulley but it does not 
represent a timing mark of any kind. There are no 
timing indicators on the front crank pulley. 
i) Loosen and remove the center bolt of the 
pulley. The bolt is installed from the factory 
using thread-locking compound on the pulley 
center bolt. 
b) The pulley does not have any timing marks on it 
nor is it keyed to the crankshaft. The pulley is 
pressed on and requires a three-jaw puller to 
remove it from the crankshaft.  
i) WARNING
 
(1) Do not use pry bars against the rear of the 
pulley or against the front cover of the 
engine. Damage to the pulley or the front 
engine cover could result. 
c) Install the puller as depicted in the diagram but 
ensure that the center bolt of the puller remains 
straight and centered on the pulley. 
d) Once the pulley has been removed you can take 
the front engine cover off by removing the two 
lower attaching bolts and the top center bolt. 
10) Remove the timing gear cover 
See Figure 7 
a) Remove the upper access panel. This is held in 
place with a single bolt.  
						

							Page 4 of 6 
 
b) Remove two bolts at the bottom of the timing gear 
cover 
c) Move the cover away from the front of the engine 
and lift upward and away from the area of work. 
11) Check the cam timing. Align all the timing marks before 
you remove the belt. The diagram shows the position of 
all the pulleys when the marks are properly aligned. 
See 
Figures 8 & 9 
a) Loosen the cam gear pulley bolts but do not 
remove them at this time. 
b) The factory manual suggests removing the 
tensioner and resetting it using a bench vise prior 
to installation. 
i) You can bypass the tensioner resetting 
procedure by inserting a 
3/64 (0.0468”) lock pin 
into the top of the tensioner to hold the 
tensioner shaft in place. 
ii) Ensure that the lock pin goes through the side 
of the tensioner and through the plunger and 
protrudes out on the other side. 
iii) If you are able to do this you can loosen the 
tensioner bolts and let it drop to the bottom of 
its adjusting range. 
iv) If the pin comes loose OR of you are not able 
to insert the lock pin then the resetting 
procedure for the tensioner must be followed 
according to factory procedures. 
12) Resetting the cam belt tensioner 
a) With the tensioner removed from the engine it is 
necessary to compress the plunger into the 
tensioner body. 
See Figures 10 & 11 
b) Place the tensioner into a vise and slowly 
compress the plunger. 
i) CAUTION: Index the tensioner in the vise the 
same way it is installed in the engine. This is to 
ensure proper pin orientation when the 
tensioner is installed in the engine. 
c) When the plunger is compressed into the tensioner 
body install the lock pin through the body and 
plunger to retain the plunger in place until the 
tensioner is installed. 
13) Remove the cam belt from the camshaft drive pulleys 
and install the adjustable cam gears in their places. 
NOTE: The DOHC engine has a staggered dowel pin 
arrangement. The intake cam alignment pin will be 
below the cam center bolt (6 o’clock position) while the 
exhaust cam alignment pin will be above the center bolt 
(12 o’clock position). The gears each have two pin slots 
in the center hub, which are used in different applications.  Install the cam gears 180° out from each 
other with one gear facing up and one gear facing 
down.  Ensure that the cams (and pins) are in their 
proper respective positions before you install the gears. 
Check all the adjustment bolts on the pulleys to 
make sure that they are tight (15 ft-lbs) and that 
both gears are set to 0. Install the center pulley bolts 
and snug them down. 
a) Set the camshafts in their proper position with the 
horizontal marks lined up. 
b) Set the crankshaft at TDC for the number 1 
cylinder. 
c) Install the timing belt on all the gears and idler 
pulleys. 
d) Apply 25 ft-lbs torque to the center nut of the 
tensioner pulley. 
i) While the tension is being applied to the pulley, 
push the tensioner up against the tensioner 
pulley bracket and tighten the bolts. 
ii) Check that the proper tension is being applied 
to the belt. This can be determined by feeling 
the resistance on the lock pin as you try to slide 
it in and out. The tension is right when you can 
slide the lock pin in and out of the tensioner 
easily. 
iii) When tensioner is set remove the lock pin. 
14) Check cam timing 
See Figures 8 & 9 
a) Rotate the crankshaft through three complete 
cycles and verify that the timing marks come back 
to the proper position. It is important that the marks 
come back to their original position. If they do not 
line up as before repeat the belt installation making 
sure that the marks are all lined up when the belt is 
installed. 
b) On some vehicles there may be slight interference 
between the timing belt inspection cover’s lower 
tabs and the tops of the cam adjustment bolts. If 
you experience this interference you can trim the 
ends of the bottom tabs of the timing belt inspection 
cover. 
i) NOTE: Having a camshaft out of proper time 
will result in very poor performance and could 
also lead to serious engine damage. 
c) Once cam timing is set you can proceed to re-
install all the items removed for the installation of 
the adjustable cam gears. Follow the reverse order 
of the installation. 
						

							Page 5 of 6 
 
 
 
Fig 1 – Splash shield and access plug  Fig 2 – Front engine mount 
  Fig 3 – PS rear mounting / adjusting bolts  Fig 4 – PS front mounting bolt 
  
Fig 5 – Removal of crankshaft pulley  Fig 6 – Weld gap on crankshaft pulley  
						

							Page 6 of 6 
 
 
 
 
Fig 7 – Layout of front cover and bolts  Fig 8 – Crankshaft front TDC mark 
 
 Fig 9 – Stock cam gear timing marks  Fig 10 – Resetting belt tensioner 
 
 Timing Belt System  Fig 11 – Belt tension adjustment 
 
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