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5.0 and Mod Motor Mustang Camshaft Selections - Lobe Lust
Take The Guesswork Out Of Choosing A Cam For Your 5.0 Or 4.6 'Stang
Horse Sense: Honesty is the best policy when selecting a cam. Wishful thinking may lead you to believe a long-duration, high-rpm, solid-roller cam is the perfect stick for your daily driven Mustang. The frustration, however, that results from the inability to get anywhere near its 7,000-rpm sweet spot will prove that bigger isn't necessarily better when it comes to camshafts for street 'Stangs. A mild hydraulic -roller would have been the better choice.
Although we've done several projects that involve designing and building 5.0-based or 4.6-liter 'Stang engines, we've never taken the time to determine exactly how many various parts go into making a hot pushrod or modular bullet.
The broad-scale answer is a lot. Obviously, there are hundreds of pieces, big and small, that contribute to a Mustang engine's overall makeup, and some components are much more important than others. As such, they require a significant amount of thought before you purchase one or several to eventually install in your 'Stang's engine.
We'd dare to bet that engine builders and hard-core engine enthusiasts will agree that camshafts rank high on the list of critical internal parts for any engine-possibly in the number-one position. Why do cams carry more weight than cylinder heads, a crankshaft, or a block? Well, one of the main reasons is rooted in the layman's definition of an engine that we're all familiar with: An engine is, and always will be, an air pump. Camshafts have the important responsibility in this air-pump system, as they ensure the valves open and close at their proper times throughout the combustion process, thus allowing fast-moving air and fuel to enter, be compressed and burned, and exit the cylinders in an efficient manner as engine speed increases.
Actually, cams can be thought of as the biggest multitaskers in an engine. They're responsible for controlling the opening and closing of the intake and exhaust valves, as well as how much and how long the valves are open, individually and simultaneously. The period where intake/exhaust valves are open concurrently is known as camshaft overlap. It's measured in crankshaft degrees and occurs only at the end of the exhaust stroke. Overlap can be a blessing and a curse. An increase in overlap can improve top-end power, but idle quality and torque down low will suffer.
When asking what's the best camshaft for a particular pushrod or modular engine, it's important to have a good understanding of duration, lobe separation, and lift, from a raw-dog technical standpoint. Duration and lobe-separation angle play big roles in establishing an engine's peak power and usable rpm range.
Duration is basically the amount of time that an intake or exhaust valve remains off its seat during a cam lobe's lifting cycle, measured in degrees of crankshaft rotation. As a rule of thumb, cams with lower/shorter duration (below 250 degrees at 0.050 inch) idle fairly smoothly (some lope, but not a lot) and make power in the low-rpm range. On the other hand, camshafts with higher/longer duration bring on the steam at high rpm and have the aggressive, lopey idle that many of us crave.
Lobe-separation angle determines an engine's torque range and the rpm at which an engine reaches peak torque. It's the distance between the intake centerline and the exhaust centerline when their values are added together and the sum is multiplied by 0.5. The intake centerline is the maximum lift point on a cam's intake lobe, measured in cam degrees after top dead center; the exhaust centerline is the maximum lift point on a cam's exhaust lobe, measured in cam degrees before top dead center.
There are two types of duration that are most commonly referred to when selecting cams: advertised (seat) duration and duration at 0.050 inch.
Advertised duration on a cam card refers to the total time (represented by degrees of crank rotation) that a valve is off of its seat-from the time it opens until it closes. It's recorded when the rocker arm is raised to a predetermined amount-usually 0.004 inch or 0.006 inch-that's set by the cam manufacturer.
Duration at 0.050 inch is the value everyone refers to when discussing cams because it's recognized as the industry standard. It's also measured in crankshaft degrees, from the point when a lifter is 0.050 inch off the cam's base circle on the opening side of the lobe until the time it falls 0.050 inch off the base circle on the closing side of the lobe.
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
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.
We've put together a small sampling of various manufacturers' shelf camshafts that are bolt-on-ready for pushrod and modular engines. While a custom cam has its benefits, we think this assortment of popular, affordable, and proven camshafts will wake up a street 'Stang with increases in power and torque that will make you glad you performed the upgrade.
Anderson Ford MotorsportAFM's N-41 hydraulic-roller camshaft is a sure bet for waking up a mostly stock (pistons, crank), naturally aspirated, street-driven 5.0 Mustang with a five-speed transmission. According to Rick Anderson, the N-41 has great manners at rpm as low as 2,000; when a set of 3.73 gears is in the rearend, the cam will spin hard up to 6,200 rpm. We recently installed this camshaft in a 5.0-liter stocker with great results. (Details can be found in a future issue.)
If nitrous-snorting stroker engines are more your speed, you may want to try Anderson's N-71 Hi-Rev cam and valvesprings. Rick says 7,000-rpm rev limits aren't a problem with this one, and it also gives a surprisingly acceptable drive on the low side (2,300 rpm).
Comp CamsComp's roster of Xtreme Energy hydraulic-roller camshafts for standard EFI 5.0s and 302-based strokers is huge, but we think the following grinds stand out as shelf cams that will easily meet the needs of most street enthusiasts who run their 'Stangs on horsepower alone or with a power adder.
The 35-512-8 is for '86-'88 Speed Density Mustangs. This cam, with 0.480 inches of intake and exhaust lift and 206 (int)/212 (exh) degrees of duration at 0.050 inch, is compatible with a stock EEC-IV engine management and adds more horsepower and torque than the OEM camshafts for those particular years.
Offering a noticeable idle for stock '87-'93 5.0s, the 35-328-8 cam weighs in with 0.513 lift and just squeaks by with piston-to-valve clearance (1.6 rocker arms are required).
Comp's 35-518-8 gives more of a lopey idle, and similar to AFM's N-41, it offers a strong midrange and top-end pull in moderately modified, naturally aspirated, five-speed 'Stangs with 3.73 gears.
The 35-560-8 lopes hard. This cam is for nitrous nuts, but it can also be applied to supercharged engines in 'Stangs that are driven on the street and run hard on the dragstrip. Piston-to-valve clearance should be checked carefully when installing this cam.
Comp also offers an Xtreme Energy compilation of cams for the 4.6- and 5.4-liter Two-Valve engines found in New Edge 'Stangs. While the mod-motor cams are bolt-in ready, upgrading to the company's beehive valvesprings and steel retainers is recommended for each of these profiles, as they all carry lift figures above 0.550 inch.
The 102500s (top photo, at top) are torque monsters. These cams improve low-rpm and midrange grunt while providing a moderate power gain in Two-Valve mods still controlled by stock PCMs. Meanwhile, the 102600 camshafts work great in street-driven modulars with gears (3.55s), intake (manifold, or throttle body/plenum), and exhaust upgrades. Custom tuning is necessary. A dialed-in program will surely bring out a distinctive rumble from this grind, and the cams also work well with power adders.
Street/strip-capable bumpsticks, the 102700s (top photo, at bottom) are for Two-Valve bullets in 'Stangs that are similarly configured (intake, exhaust) to those that shine with the aforementioned 102600 camshafts. However, the increased lift in these cams requires using aftermarket pistons with deep valve reliefs, as well as custom tuning and 3.73 or 4.10 gears. A really aggressive idle is their signature, and they're definitely blower-, turbo-, and nitrous-compliant.
You didn't think Comp would leave Three-Valve 4.6s out of the mix, did you? There's no chance of that happening. The Xtreme Energy series continues all the way through S197 powerplants, with three stages of performance camshafts for trey valves that see daily street usage and hard-core racing abuse.
Stage One 127150s (bottom photo, at top) are good camshafts for daily driven, light-performance street Mustangs. The cams offer a noticeable idle and a torque hike that's definitely noticeable at the lower rpm range.
Stage Two 127300 cams (bottom photo, at middle) thrive with five-speed trannys and 3.73s in naturally aspirated trey valves with additional minor performance mods.
Stage Three 127350s (bottom photo, at bottom), while somewhat streetable, are more race-oriented cams that make a blown, turbocharged, or nitrous-pumped Three-Valve come alive in the upper rpm. Engines with strong bottom ends and high-flowing cylinder heads with beehive springs and steel retainers are required for these cams.
Crane CamsCrane brings PowerMax cams to the table for '99-'04 Two-Valve 4.6 engines. The forged-steel cams feature a dual-pattern design in which intake and exhaust lobes are individually optimized for better efficiency.
Best-suited for daily use, 379601 camshafts provide a smooth idle and a nice increase in low-end torque.
The 379611 offers a more pronounced idle and great street performance from mod motors that rely on blowers and nitrous for increased oomph.
Great for naturally aspirated street/strip 'Stangs, 379621 cams require some custom tuning, and they yield a fairly distinctive lope.
For harder-core, rough-idle, Two-Valve cams like the 379631, it's best to have a built bottom end and higher-than-stock compression.
Crane recently unveiled its new bumpsticks for Three-Valve mod motors. Similar to ProMax camshafts, the Zcam series features dual-pattern profiles. It requires spring and retainer upgrades as well.
Leading off the collection is the 399501. This grind offers a smooth idle and good daily-driver street performance. The cams are predominately made for naturally aspirated, mostly stock engines, but they can also be used in mild turbo or nitrous applications.
Zcams for S197s with power adders are the 399511. Piston-to-valve clearance may be dicey with these camshafts, so tuning is critical if you decide to use them.
Camshafts are designed for naturally aspirated engines in stick-shifted S197s. The 399521 cams want compression and can make great power with proper PCM tuning.
Ford Racing Performance PartsMany old-guard 'Stang nuts probably agree that Ford Racing Performance Parts' B-, E-, F-, X-, and Z303 camshafts started it all when it comes to hydraulic-roller bumpstick upgrades for '86-'93 5.0 Mustangs. Everyone knows about FRPP's alphabet soup of cams, either through personal use of one or several of the different grinds, or simply by hearing other enthusiasts talk about the B cam or X cam underhood in their Ponies.
Hydraulic- and Solid-Roller CamshaftsRoller camshafts have been standard equipment in Mustang engines since 1985. The roller nickname for these camshafts, as well as their hydraulic and solid prefixes, are derived from the type of lifters that are used with each of them.
To answer a frequently asked question regarding 5.0 camshafts, the E303 (E cam) is the biggest FRPP cam (0.498-inch intake/0.498-inch exhaust) that can be used in an engine with a stock bottom end. Anything bigger requires piston upgrades to eliminate clearance issues.
Livernois MotorsportsLivernois has been at the forefront of forced-induction Mustang performance for several years. These two samples of its 0.475-inch-lift camshafts for turbocharged and supercharged Three-Valve GTs (right) and Four-Valve Cobra applications (above) will definitely put fire under an '05-'08 'Stang's hood. Although lift values are the same for these cams, their variances in duration at 0.050 inch are key to their ability to generate killer high-rpm power and impressive torque down low.
Hydraulic lifters are self-adjusting and feature a plunger and spring combination that regulates oil pressure inside the lifter body. Solid lifters are one-piece units that don't have oil-regulating plungers or springs. The small wheels at the bottom of both types of lifters are the actual rollers. Rollers reduce cam-to-lifter friction, which helps aggressive cams reach higher speed and lift levels.
When it comes to making a choice between hydraulic-roller cams and solid-roller cams, you need to have a good idea of the usual rpm of your 'Stang's engine.
Hydraulic-roller cams are your best bet for street and moderate race applications. As we've explained in this report, there are plenty of profiles available, and custom grinds can be developed to give a 'Stang's engine a big boost in performance. Other great qualities of hydraulic camshafts are that they are low-maintenance, don't require any adjustment once set, and are quiet. Hydraulic-rollers are perfect for engines that don't see more than 6,500 rpm on a regular basis.
Although there are plenty of solid-roller setups on the street, they're more racebred than hydraulic-rollers since they're intended to support engines that spend most of their running time in the 7,000-plus-rpm range. The hardware associated with a solid-roller cam (lifters/rocker arms) is typically noisier than hydraulics. Because of the way solid cams are designed, the lifters require frequent checking and lash adjustments for proper piston-to-valve clearance, which could become a pain for engines that see a lot of street time.
Camtastic ToolsWe had to include a few cool cam-related tools in this story. While there's probably many more specialty items associated with this subject, we think this group of user-friendly equipment offers something for everyone, from do-it-yourself to master-Melvin 'Stangbangers.