Edelbrock performer air gapÂ manifold suit SBC. Design features an open air space that seperates the runners from the hot engine oil resulting in a cooler denser charge for more power.Â Rev range idle to 5,500rpm. Spread bore and square bore pattern. Dual plane design. Manifold height front 3.72″, rear 4.92″. Port size 1.14″ x 1.88″.