Edelbrock has had a long-standing relationship with famed racer and engine builder Pat Musi, and the technical partnership has produced numerous performance parts and crate engines that benefit both the enthusiast and racing market segments. The 12-degree Big Victor cylinder head for big-block Chevy engines is their latest collaboration, and we sat down with the team at Edelbrock to find out all of the details on the product’s design, its target customer, and performance.
The Big Victor Specifications
The Big Victor cylinder head for big-block Chevy applications (P/N: 618270) is sold as a bare cylinder head, but comes fully CNC-machined. It features a 12-degree valve angle, 498cc raised intake ports and 82cc combustion chambers. To move the atmosphere through the ports, Edelbrock has machined the head to fit 2.500-inch intake and 1.800-inch exhaust valves. Each head is also fitted with copper valve seats, and a valve job is performed.
For those not in the know, the 12-degree valve angle is in reference to the angle of the valve from the deck surface of the cylinder head. We queried our sources as to why the 12-degree valve angle was chosen, and Jamie Wagner, Edelbrock cylinder head and crate engine product manager, gave us the answer.
“The valve angle is generally driven by port shape, and to maximize airflow into the chamber. Some like the shallow valve angle because it can improve valvetrain operation, as well. The 12-degree valve angle was an evolution of the other various cylinder head designs we have had over the years. It lends itself well to the design of the intake port, which is very important to engine performance. It makes for a good port entry and exit design when looking for optimum port flow characteristics,” Wagner tells us.
In racing applications, port shape has become less of a curve and more of an arc to be able to move air more quickly. The angle of the valve in relation to the port can also affect how quickly the air moves into the combustion chamber. By angling the valve tip laterally and outwards towards the exhaust port, it opens up the entry into the combustion chamber. In doing this, however, it does move the valve head closer to the cylinder wall, so the valve tip is angled or canted 6 degrees longitudinally away from the center of the cylinder bore to move the edge of the valve head away from the cylinder wall.
“The 6-degree lateral tilt is to help offset some of the reduced valve-to-cylinder-wall clearance from the 12-degree lateral tilt, which puts the valve head closer to the wall,” Wagner explains. “The 6-degree cant tilts the intake valve edge away from the cylinder wall to help keep the valve from being shrouded on that side, which helps flow into the cylinder.”
As the Big Victor cylinder head is designed for larger cubic inch, big-block engines, it’s no surprise that the flow numbers are big, too. The intake port flows 523.8 cfm at 1.00-inch of valve lift, and the exhaust port offers 335 cfm of flow at the same impressively huge amount of valve lift.
To round out the cylinder head components, Edelbrock worked with the valvetrain experts at Jesel Valvetrain to develop a rocker arm system that is a one-piece, drop-in component available through Jesel. It is designed, of course, to provide stable and reliable valvetrain actuation throughout the engine’s operation.
Casting For Success
It’s important to note that the Big Victor head from Edelbrock is a cast product rather than machined from billet. We asked Edelbrock’s Director of Product Management, Mike Sanders, about the product’s cast construction and what it’s advantages and disadvantages are.
“Billet will always be superior because the billet aluminum alloy is denser. Edelbrock understands this and our state-of-the-art foundry has developed a premium aluminum alloy that is put through a H.I.P. (Hot Isostatic Pressing) process and is precision heat treated to create a dense cast aluminum alloy with high tensile strength to withstand high cylinder pressures associated with today’s high-horsepower engines,” Sanders explains.
“Starting from a solid chunk of billet requires a significant amount of machine time,” Wagner added. “There are additional costs involved and it’s fairly more expensive over cast. The H.I.P. process gets you very close to the material of billet. It reduces casting micro-porosities and improves the casting’s overall strength.”
Interestingly enough, Wagner explains that the head is initially cast larger than the finished product, and then the H.I.P. process compresses it, which aligns the material’s molecular grain, making it more dense, and thus produces a stronger and more durable casting.
Speaking of aluminum, the Edelbrock Big Victor cylinder head is cast from A356-T6 and is produced in the USA at Edelbrock’s own foundry. Then, the manufacturing process continues with machining processes.
“The heads are fully CNC-ported at our Race Center using our Centroid five-axis CNC,” Sanders explains. “Each head is inspected by Pat Musi to make sure that the valve job and CNC transitions are flawless. All of this together gives the racer a pro quality cylinder head at an affordable price point.”
Pat Musi’s Golden Touch
In working with someone as experienced and successful as Pat Musi and his Pat Musi Racing Engines shop, Edelbrock has a direct connection with someone whose engines regularly compete at the highest levels in drag racing, and often win races as well.
“Pat has been involved from the inception of the Big Victor 12 though all of its current revisions,” says Sanders. “His years of engine building and tuning experience have contributed to the premium features of this cylinder head and have given Edelbrock a unique advantage in this segment of the raised, spread-port, rolled-valve-angle market. The latest revisions include refined CNC bowl blending, copper valve seats and conical chamber modifications for improved tunability.”
“Musi took the original head and recommended changes,” Wagner says. “He had a lot of input on the chamber, valve angles, and spring rates to make them a little more conducive to nitrous use. You’re always fighting detonation in power-adder combinations and do all you can to mitigate it. Flattening the chamber helps keep the top of the piston flat, which helps reduce the hot spots.”
“In the case of the Big Victor 12 degree, we have designed a specific exhaust port and added soft chamber modifications to help with cylinder evacuation and tunability that is associated with high cylinder pressures caused by power adders,” Sanders adds.
The soft chamber modifications Sanders mentioned has to do with previously existing sharp edges in the combustion chamber.
“Typically, you don’t want sharp edges inside the combustion chamber, as they can hold heat and cause pre-ignition,” Wagner explains. “We changed the chamber shape to a cone shape rather than a radius, which softens the outer edge up.” Wagner noted that the downside to this change is that it increases the volume of the chamber, which may require a different piston to obtain the compression ratio you want, but that’s a small price to pay for improving the durability and longevity of your engine.
The 12-degree Edelbrock Big Victor Cylinder Head — Who Is It For?
With a good idea of what the Big Victor cylinder head is about from a technical standpoint, we asked Sanders and Wagner about the applications that this cylinder head is best suited for.
“This head was purpose-built for maximum competition. Its Pro Stock-inspired, spread-port design and improved valvetrain allows this head to easily feed large cubic inch, high-RPM engine combinations with ease,” Sanders explains. And when Sanders says “large cubic inch,” he’s talking about 598 cubes and bigger.
Wagner adds that the Big Victor cylinder heads will likely be used by racers competing in categories such as Super Comp, Super Gas, Comp Eliminator, Top Sportsman, and Top Dragster. He also notes that it’s a good option for no-prep and 632 grudge racers, and that land-speed competitors will find it to be an appealing option for various classes in that type of racing, as well.
Edelbrock has always had a good reputation for quality products that perform well and last, and we wouldn’t expect anything different from its Big Victor cylinder heads. With the technical knowledge that Pat Musi brings to the table, it’s sure to have the most up-to-date modifications to its design to ensure it keeps up or surpasses the competition.