AEM 23-851BK Tru-Time Adjustable Cam Gear - Manual (Page 2)

You have just purchased the BEST adjustable cam sprockets available. These AEM
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.