Tom Wilson
December 1, 2002

Horse Sense:
Some guys want a cam with a lumpy idle but near-stock driveability. Well, forget it. Long duration and overlap are what give a cam that racy idle and blazing top-end horsepressure, along with lousy mileage, poor low-rpm power, and annoying driveability. You can't really have one without the other, especially on a computer-controlled EFI engine that does its best to smooth out the idle.

Got a hankering to power up your Pony? Been through all the bolt-ons and still looking for more? Ten pounds of boost not enough? A camshaft may be what you're looking for.

Camming 5.0 H.O. engines is more popular than ever, and there are some great choices available. In fact, there are so many camshafts for small-block Fords that we've polled the industry to see what the experts recommend for a few popular 5.0 combinations. Besides getting the shortcut to some promising 5.0 cams, the process has given us insight into the interesting and challenging world of cam operation and selection.

Opening Events
Truth is, the stock cam in your 5.0 is-if a bit tame by today's fire-breathing performance standards-a fairly nice piece already. Ford uses a steel camshaft with hydraulic roller lifters. The hydraulic part means the valve adjustment is automatically made with each valve event, saving us all from periodic valve-lash adjustments. Once a fair source of man/ machine bonding, lashing a V-8-especially when the upper intake manifold must be removed to access the driver-side valve cover-is definitely more chore than high-tech tinkering. We'll take the hydraulics, thank you.

Choosing a cam is all about knowing what you want from your car. Drag racing, for example, calls for a high and typically narrow rpm range to work with the short rear-axle gearing. This isn't exactly fun in a daily driver, so the trick is deciding just how racy to be. All cam makers report customers always ask for too much cam because they crave the high-rpm rush. Of course, two weeks later, most customers are ready for something a little more civilized on the street.

As for the roller part of the lifters, Ford put those there to reduce friction and thus increase gas mileage. By holding down your right foot, you can translate this mileage increase into more horsepower, so no one is arguing with the roller lifters. Roller lifters also allow more aggressive valve events. In other words, the valves can be opened and closed more quickly when using roller lifters. This increases power.

All 5.0 roller cams are steel, not cast iron. The combination of durable steel and roller lifters means cam and lifter break-in is a nonissue. Changing 5.0 cams means not having to bite your nails to see if a lobe went flat or a lifter collapsed during the critical break-in period, because with roller lifters, there isn't any break-in. All these things make the stock camshaft architecture a fairly good power producer while still offering a smooth idle. We've seen some impressive power from stock-cammed 5.0s, especially the supercharged variety.

The Specs
That said, an aftermarket cam-shaft could significantly boost engine output, more so than many of the simple bolt-ons. This is because the camshaft controls so much of what ultimately happens inside the combustion chamber.

Think of the camshaft as a mechanical computer for the intake and exhaust valves. The camshaft tells the valves when to open, how fast to open, how far to stay open, how long to stay open, when to close, and how fast to close. These are vital engine power-building parameters.

Open-tracking and other road-racing cars are easier to cam because the power that's fun on the track is just a hotted-up version of what's fun on the street. A broad torque band that pulls off the slower corners is a must, along with a little extra-high-rpm oomph on the straights.

To get started on specifics, the stock cam in 5.0 H.O. engines, while varying slightly in detail over the important '86-'93 period, is nominally the same. Its important specifications are listed below.

VALVE LIFT DURATION LOBE
CAM INT./EX. AT 0.050 IN SEPARATION
Stock 5.0 0.444/0.444 210/210 115

In other words, the stock camshaft opens both the intake and exhaust valves 0.444 inch at maximum valve lift. Both valves are open 210 degrees of crankshaft rotation when measured from 0.050 inch of valve lift (an industry standard), and the distance between the maximum lift of the intake cam lobe to the maximum lift on the exhaust lobe is 115 degrees.