AEM 23-831BK Tru-Time Adjustable Cam Gear - Manual (Page 2)

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.