While most manufacturers of small block Chevy intake manifolds have designed their units around 350 c.i. engines, World Products has developed a very efficient manifold for 383 c.i. & larger engines that's proven to increase performance by 15-25 horsepower over the competition.
In addition to out-powering the competition, it's important to note that these single plane manifolds are designed to operate most efficiently in the 2500 to 7500 RPM range, and have the low-end throttle response and torque comparable to a dual plane. Look inside the plenum and you'll see a "turtle" on the manifold floor that helps increase velocity for improved bottom-end performance.
Holley 4150 carb flange.