User Manual

COMP Cams®
3406 Democrat Rd.
Memphis, TN 38118
Phone: [phone] Fax: [phone]
www.compcams.com
Part #COMP4-119
Revised 6/13/08
Read This Pre-installation Guide Before Installing Kit !!!!!!!
Ford 4.6L and 5.4L 3-valve engine cam phasers, how they work, their limitations, and how
COMP uses them for making more power
What are cam phasers?
Ford’s cam phasers are specially designed, computer controlled cam gears that have the ability to adjust camshaft position
while the engine is running. They are used on all 2005 and newer, 3-valve Ford modular engines. Since the modular engine
uses two camshafts, one for each side of the engine, two cam phasers are used per engine.
How do they work?
Engine oil is pressure fed through a series of passageways in the cylinder heads and camshafts, out to the cam phasers. The
engine computer controls a pair of solenoids that adjust this oil flow into, and out of, a series of chambers inside the cam
gears. Located inside these chambers are vanes, attached to a free-floating central hub. The hubs are directly attached to the
camshafts, and as oil is allowed into and out of these chambers, the position of the cam can be retarded up to 60 crankshaft
degrees.
Why did Ford put them in the engine?
Ford’s primary reason for using cam phasers was to increase the engine’s efficiency by reducing its pumping losses.
Basically, when the cams are retarded 20-40 degrees, during part throttle engine operation, it takes less power to turn the
engine over. This helps to increase the engine’s fuel efficiency, but an additional power benefit is also realized by being
able to position the camshafts for maximum power, regardless of what rpm the engine is running at. This results in an
engine that makes more torque and horsepower and extends the high rpm power-band by an additional 800-1000 rpm.
Why should I modify the cam phasers with COMP’s limiter kit?
If there is a downside to the cam phasers as designed by Ford, it is that they have such a wide range of movement. Since the
cams can theoretically be retarded by up to 60 degrees, there is very little piston to valve clearance in the engine. This
minimal piston to valve clearance limits us to fairly small cam profiles with very little overlap; not the best for making
maximum power or achieving an aggressive idle sound.
What does COMP’s cam phaser limiter kit do?
COMP’s Cam Phaser Limiters replace a plate on the back side of the factory cam phaser. These limiter plates are made
with posts that extend into the cam gear’s oil chambers. These posts take up excess volume that would normally be used by
the factory cam gear for movement. By installing COMP’s cam phaser limiters, the cam design window opens up, allowing
you to install big, powerful camshafts with safe piston to valve clearances. At the same time, by keeping up to 20 degrees
of movement available, all of the wide-open throttle benefits of the cam phasing can still be retained. The normal maximum
retard the cams see at wide-open throttle is only around 9 degrees with factory programming.
Why can’t I just reprogram the ECU to limit cam phaser movement?
Since Ford’s factory engine computer is fully programmable, the question arises as to why you can’t simply program in the
limits and not bother with mechanically limiting the cam phasers. Theoretically you could do that, but a problem arises if
something happens that would cause the engine’s rpm to shift faster than the cam phaser controls can react to. For example,
if you ever missed a shift, broke a driveline part, did a clutch dump on a sticky set of slicks, or anything that could for a
split second cause the cam phasers to get out of their programmed limits, the valves could crash into the pistons. By
mechanically limiting the maximum movement of the cam phasers, total engine safety is assured when running big
performance cams in these engines.
Do I have to reprogram my engine’s computer after installing COMP’s Cam Phaser Limiter Kit?
Yes, you MUST have your engine’s computer reprogrammed for the engine to operate properly after installing the cam
phaser limiters. The Ford factory computer does a diagnostic sweep test of the cam phasers upon start-up. If the computer
cannot get the cam phasers to reach their programmed maximum limit, an error mode occurs. The engine will continue to
run, but the cam phasers will not function properly. The guidelines for reprogramming are simple; just make sure that the
maximum retard amount entered for any of the cam phaser tables in your tuning software does not exceed 20 degrees.