The carburetor is king; long live the king. Or so goes the saying, but it's most definitely true in the realm of the carburetor in all of its configurations. Given the advent of electronic fuel injection and its growing popularity, it's still amazing when one sees just how many street rods, custom rods, classic trucks, kit cars, etc., still use the venerable carb. And why not-it is a well thought-out piece of equipment that has served us well for over 100 years and continues to do so today. And as goes the carburetor so goes the intake manifold.
In our small corner of the automotive aftermarket, street rodders have managed to employ everything from single-barrel carbs to six carbs on a single intake. In our world, the single four-barrel, three twos, and the dual-four-barrel are king. With this in mind, let's take a look at one of the latest offerings from Edelbrock-the RPM Air-Gap Dual Quad manifold and carburetor kit for both the Generation I small-block Chevy made from 1955-86 (265 to 400 ci) and for the Gen-I small-block Chevys with 1996-and-later Vortec iron heads as well as Edelbrock E-Tec aluminum heads. The RPM Air-Gap Dual Quad kit is designed to give you everything you need to convert from a single four-barrel to a dual-quad intake system for your small-block Chevy in an afternoon. The kit includes the RPM Air-Gap Dual Quad intake, two 500-cfm Thunder Series AVS carburetors (one manual and one electric choke), progressive throttle linkage and carburetor fuel line, and intake manifold gaskets.
The manifold (#7525), in its as-cast finish, is intended for the '55-86 SBC cylinder heads, while the Vortec manifold (#7526), also in its as-cast finish, is intended for the 1996-and-later Vortec heads or Edelbrock E-Tec heads.
For those who may not be familiar with Edelbrock's manifold classification, the Performer RPM manifolds are ideally suited for the street with a performance range from 1,500 to 6,500 rpm. They are a dual-plane, high-rise intake with 180-degree firing order that accounts for excellent top-end performance while retaining the ever elusive, but absolutely required, good throttle response to make your street rod drivable. According to Edelbrock technicians, "The larger plenums and runners match the free-flowing exhaust, high-lift cams and other modifications of a high-output engine. They are intended for high-performance street engines that run up to 6,500 rpm."
Now take the proven performance of the Performer RPM manifold and integrate Edelbrock's award-winning Air-Gap design and you now have the next generation in Edelbrock intake manifolds-the performer Air-Gap and RPM Air-Gap. Again, according to Edelbrock, "The air-gap design features an open air space that separates the runners from the hot engine oil resulting in a cooler, denser charge for more power. RPM Air-Gap manifolds are modeled after Performer RPM intakes for high-performance street power from 1,500 to 6,500 rpm, and the new Performer Air-Gap manifolds are ideal for street performance from idle to 5,500 rpm."