This collection of high-lift, long-duration cams, valves, and springs, among other thngs (PNM-6550-T46), is made specifically to maximize the performance potential of FRPP's high-flow, '03-'04 Cobra, Four-Valve cylinder heads. The camshfts generate up to 7,000 rpm without sacrificing anything on the torque side and doesn't make street cruising possible.
An interesting thing to keep in mind for 5.0 cams is when you're stepping up to a solid-roller from a hydraulic camshaft, duration at 0.050 inch for your new cam must be raised 8-10 degrees in order to achieve the same duration at 0.050 inch.
Lift is the third and final camshaft spec that needs to be understood when selecting a cam. Similar to duration, lift also is referred to in two flavors: lobe lift and valve lift.
Lobe lift is a value that's ground into a camshaft when it's made. It's the cam lobes' overall height above the base circle (measured in thousandths of an inch) and the amount that cam lobes actually raise lifters inside their bores.
Similar to advertised duration, valve lift (also known as gross valve lift) is the cam spec that engine Melvins like to reference most. Valve lift is the product of lobe lift multiplied by the rocker arm ratio you've chosen. The value represents the distance a valve is raised off its seat when a cam lobe is at its highest point.
Cylinder-head characteristics also have a big influence in cam selection. As many of us have discovered while browsing Mustang-related Web sites, cylinder heads' flow numbers is one of the most talked-about subjects in engine-related message forums. Outside cyberspace, most head manufacturers and porters are quick to boast about how well their heads flow at 0.700 inch of lift.
Noted camshaft guru Ed Curtis of FlowTech Induction Systems says, "Massive flow at 0.700 inch is fine, but a cam's lobe is only at 0.700 inch for a short time-if it even really reaches it. When it comes to picking a good performance camshaft for 5.0s or mod motors, head-flow numbers that range between 0.300- to 0.500-inch lift are the values that should be used because cam lobes are in the mid-lift ranges longer."
Here are a few additional technical factors about an engine and a 'Stang itself that should be taken into account when developing a cam profile:
* Total cubic inches and compressionratio* Naturally aspirated, nitrous oxide, orforced induction (turbo/supercharger)
* Intake (manifold size, plenum, throttle body)* Exhaust (headers, manifolds)
* Rearend gear ratio* Tire diameter
* Transmission (automatic/manual)* Weight
* Altitude engine is normally used at* Desired idle quality
For the Three-Vavle engines in S197 Mustangs, AFM offers a full line of Hi-Intensity and Hi-Rev cams, with profiles suted for bone-stock or highly modified engine applications (naturally aspirated--N-23 and supercharged--F33).
While this is quite a list, your camshaft's design should be spot-on compatible with all of these factors-and ultimately your specific goals (street-only, street/strip, full-drag, and so forth)-if you want your Mustang's engine to perform at its optimum potential.
We can't detail every granule of hard-core theory that applies to camshaft selection, but we hope you will keep this information in mind when setting out to build a killer bullet for your Pony.
Novice 'Stangbangers who want to step up their performance game should consult with a knowledgeable engine builder or cam specialist for guidance on picking the best cam for their engine combo. Good resources include Ed, Rick Anderson of Anderson Ford Motorsport, or the tech representatives at any of the popular cam manufacturers.
Enthusiasts with more confidence should try Comp Cams' CamQuest 6 cam-selection software. We detailed this cool and helpful program in the Tech Inspection column in our June '07 issue (p. 236). The software requires a user's input of all the key specs for a proposed engine and power adder setup, then searches through Comp's huge database of camshafts and associated hardware, including valvesprings and rocker arms, among other things, to offer suggestions for products that will help your effort. Another cool thing about CamQuest 6 is that it's available as a free download from Comp's Web site (www.compcams.com), so we suggest you add it to your desktop.