Designed for large cubic-inch or high rpm drag racing big-blocks Chevy Spread Port with Edelbrock Big Victor, Dart Big Chief or Brodix Big Duke cylinder heads, these manifolds have an average runner area of approximately 4.75 sq. in. The port exits have been reduced to accommodate the wide variety of intake port sizes and require port matching. These features, combined with approximately 5% taper in runner cross-sectional area, give better top end horsepower while maintaining consistency and throttle response off the stop. All applications are equipped with a 4500 Series flange and will accept 2.25” throttle body butterflies without a spacer or modification Big-block drag race engine with high air flow requirements 3500-8500 rpms. Tall deck height 10.200″ Manifold height 9.530″. Special order item 2-5 business days. Please e-mail with questions.