Overall Length: 18.5" front-to-back
Port Dimensions: 1.375" x 1.375" (can be opened up to approx. 1.5" square)
Exhaust Flange Outlet: 2" I.D. (can be opened up to approx. 2.25")
Exhaust Flange Thickness: 5/16"
Exhaust Flange Bolt Pattern: 2-bolt, 3-1/8" center-to-center
(Please use the GIF chart below along with the following description.) "A" dimension, right angle to the exhaust port flange of the head, is 5.25". "B" dimension is in 2 measurements: from the centerline of the bolt holes UP = 4.5"; and from the centerline of the bolt holes DOWN = 4".
Header Dimensions (GIF)
Note: One end bolt hole is slotted to the end of the casting. This will allow the installer to start one bolt into the engine to hold the gasket, and then slip the manifold onto that bolt and use that to support the manifold/gasket to make alignment and insertion of the other bolts much easier.