April 1, 2007
After installing the Edelbrock Performer heads, the 302 blasted out 383 hp and 364 lb-ft of torque, for a gain of 78 hp peak to peak. Near 6,000 rpm, the difference in power was an astonishing 92 hp.

The name Edelbrock conjures up all manner of performance components, and for good reason. Enthusiasts have relied on Edelbrock performance components for over 65 years. Tucked in with all the intake manifolds, camshafts, and exhaust systems are a wide variety of cylinder heads. Edelbrock offers everything from mild performance bolt-on replacement heads to CNC-ported race heads. Much to the delight of Ford fans, Edelbrock recognized the importance of the 5.0L Mustang market and began offering a number of different aluminum cylinder heads to replace the stock cast-iron 5.0L heads. Our testing for this article centers on its 50-state-legal aluminum Performer Ford heads.

The California-based company offers a three-tiered approach to Ford performance cylinder heads. Edelbrock fans now recognize that the designations Performer, Performer RPM, and Victor Jr. indicate different performance levels. This approach is a wise one, as not every builder has maximum performance (and associated trade-offs) in mind. If one head was right for every application, then all of the manufacturers would zero in on a lone design and we would be left with no cylinder-head choices.

Before getting to the impressive power numbers, it is important to understand what part the heads play. Like any internal combustion engine, the Ford 5.0L 302 produces power by processing air and burning fuel. We use the word processing to designate the fact that any airflow that goes in must also find its way out. The more air it can process, the more power it will produce. One way to increase the amount of airflow is to increase the size, or displacement. Bigger-bore pistons and longer stroke cranks help draw in and push out more air. That is why bigger motors make more power than smaller ones. Another method is to force air into the motor by some form of forced induction. The final method is to reduce restrictions inherent in the basic motor, or improve its ability to breathe. For this article, we will concentrate on this latter method.

Improving the ability to breathe means removing (or greatly reducing) any component or design that may hinder the ability to process air. Starting from the exhaust forward, this means providing the motor with a free-flowing exhaust system. With the exhaust taken care of, we can turn our attention to the intake. The intake tract for a carbureted motor (like out test mule) begins with an air filter, but the main component is the carburetor. Always select a carburetor sized for your application, and don't be afraid to ask a pro if you are unsure. The intake manifold is next, and it should be chosen based on flow and the intended operating rpm. The manifold should work with the cam timing to effectively determine the power curve of the motor. The final elements in the equation are the cylinder heads.

A simplistic overview is that the cam timing and intake manifold determine where the motor will make power and the head flow determines how much. Of course, things like compression, cubes (displacement), and carburetion all play a part in this dynamic equation, but without a good set of cylinder heads, your combination will likely fall on its proverbial face. While maximizing cylinder-head flow is critical to optimum performance, it is every bit as important to remember that bigger is not always better. Remember we said the engine is a dynamic equation? Just like the cam timing and intake design, the head port volume (and airflow) must be sized to operate effectively in a desired rpm range. Installing a set of wild NASCAR Yates heads on an otherwise stock 5.0L 302 would be a monumental waste of time. The rest of the components in the stock motor (intake, cam and exhaust) would sign off well before the head started to reach peak efficiency. The result would likely be a lazy motor that makes less power than the stocker.

For this reason, Edelbrock decided to instrument the tiered approach to cylinder heads, as well as intakes and cams. Obviously, it recognizes that a mild 302 requires different cylinder heads than a wild 408 stroker. For our test, we selected heads from the lowest of the three tiers, namely a set of 50-state-legal Performer Ford heads (PN 60329). Edelbrock also offers a set of bolt-on replacement Performer heads for a 5.0L 302 (PN 60289), but we opted for the heads set up to accept adjustable rockers. The Performer 5.0/5.8L heads were set up to accept bolt-down rockers, but we liked the freedom of the adjustable rockers, not to mention not having to deal with rocker shims.

The Performer heads featured A356-T-6 aluminum construction to reduce curb weight, compared to stock cast-iron heads, and a 1.90/1.60 valve combination. The Performer heads are also available with 2.02 intake valves (retaining the 1.6 exhaust valves) under PN 60349, but we opted for the smaller valves. Care must be taken with the larger valves as they reduce piston-to-valve clearance. Our Probe Racing pistons were equipped with generous notches, so clearance was not an issue.

In addition to the 1.90/1.60 valve combination, the Edelbrock Performer aluminum heads were set up with a spring package suited for our hydraulic roller cam. The spring package produced 125 pounds of seat pressure and 290 pounds of open pressure at 0.550 lift. Edelbrock springs also allowed plenty of room before experiencing coil bind (up to 0.650 lift). The springs offered plenty of pressure for the mild 0.544/0.555-lift hydraulic roller cam we intended to run in our 302. The Edelbrock heads also featured a number of other nice features, including CNC port-matched intake and exhaust ports, heli-coiled rocker and exhaust bolt holes, and a 51/48-inch-thick deck surface. The heads also came assembled with springs, retainers, and guideplates. It should be noted that the head bolt holes in the Edelbrock Performer heads came drilled to accept 1/2-inch head bolts/studs. Bolt bushing kits are available from both Edelbrock and ARP to allow use of the Performer heads with the smaller 7/16-inch head bolts/studs used on the 302 Windsors.