A dual-plane manifold splits the plenum so each cylinder draws through a longer runner, and that is what builds the low and midrange torque a street 289 or 302 actually uses. This one is tuned for idle to 5,500 rpm, which suits a stock or mildly cammed engine in a Mustang, Ranchero or early truck far better than a single-plane race manifold that only wakes up past 5,000.

Edelbrock 2121-CP Performer Manifold Specifications:

• Dual plane design, cast aluminum, chrome plasma finish.
• Fits small-block Ford 289 and 302 V8 engines.
• Idle to 5,500 rpm basic operating range.
• Square bore carburetor flange. Heights: 3.5 in. front, 4.12 in. center, 4.75 in. rear.
• Non-EGR casting. Gaskets are not included.