Creating the Impossible – Mid-Length Headers for Big Block GM A-Bodies

Published April 26, 2017 by hedmanperformancegroup

nikon photos 101Hedman Hedders specializes in helping vehicles unlock their true power potential and is always looking for ways to diversify ourselves from the rest, whether that means creating products for more vehicles or creating a new product segment like we did with our mid-length headers.

For years, the header market has consisted of either shorty or long tube headers – depending on your application and use.  Long tube headers provide better scavenging of exhaust gases and produce more power, but can create ground clearance issues underneath due to their longer design, especially with the much lower ride heights of today’s modified cars. On the other hand, shorty headers are an improvement over factory manifolds, but don’t produce nearly the power of long tubes. This has left many people wanting a happy median where they can benefit from more power without the worry of damaging their exhaust whenever they go over a speedbump or enter a driveway.

We have created an entire catalog of Mid Length headers for the most popular vehicle and engine combinations, but the big block-powered GM A-Body presented a unique clearance challenge that no other header manufacturer had been able to address. When you try to build mid-lengths for Big Block A-Bodies using traditional header design techniques, you run into clearance issues between the primaries and the steering shaft as well as with the collector and the frame rails or bellhousing. To overcome these issues, a series of complicated bends need to be performed to successfully clear nikon photos 088the vehicle’s components while still evacuating the exhaust gasses in an efficient manner. These complicated bends could only be accomplished with the use of a state of the art CNC tubing bender and a very skilled welder – which we have plenty of.  Now we just needed a car for testing.

Lucky for us, a local enthusiast by the name of Bob Kellison reached out to us looking specifically for a mid-length style header for his 1966 Chevrolet El Camino. Bob has been a car guy all his life, getting his passion from his father who was a mechanic. Bob decided to go into the paint and body side of the business where he started out at 14 years old and now, 47 years later, he is still doing what he loves. When asked why he decided to be a painter, Bob said, “You can have a perfectly running and driving car and people will only see it as a car. But a good paint job is what grabs their attention, draws them in, and makes people see it as rolling art and form a connection with it.” Bob is truly passionate for what he does and his El Camino ended up being the perfect candidate to use to design our big block A-body headers thanks to its clean chassis, unmodified suspension and 427 big block under 20170212_161014the hood.

Bob’s El Camino started its life as a six-cylinder, three-on-the-tree car, but this quickly changed when Bob took ownership of it five years ago. He immediately removed the old engine and transmission to make way for a more powerful 427 big block bored .060 over with oval port heads, GM aluminum intake, and Holley 800 cfm carburetor, along with a Turbo 400 automatic transmission. The one thing missing from the equation was a good set of headers, but Bob didn’t want long tubes due to the ground clearance issues, which led him to wanting a set of mid-lengths.

0809160818aAfter Bob called us looking for headers for his car, we decided to take on the difficult task of designing the mid-length headers for Bob because we knew our combination of skilled craftsman and state-of-the-art tube bending equipment could create the complex bends necessary for these headers. After countless hours of R&D and fitment testing, we came up with a design that both fit and flowed great.  This design was then digitized and programmed into our CNC mandrel tube bender, we were ready to precisely recreate the individual primary tubes for the production headers.

While these computerized tube benders have given us the ability to create highly complex shapes that were never 0809161714~2before possible, we still rely on old-world craftsmanship to assemble and build all of our headers in the USA.  From assembly to swaging, welding, and coating, every set of Hedman headers is built by passionate and talented craftsman and master welders.

The end result is the first production mid-length big block A-body header, which is truly a work of art and feat of engineering when you see all of the work that went into it nikon photos 070and how complex the bends really were to make this a reality. We would like to thank Bob Kellison for letting us use his vehicle to build the prototype headers and every one of our talented crew involved in the project. It is innovation like this that keeps pushing us to be the best we can be and to continue hand making the best headers right here in the USA since 1954.

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