FAST Intake Manifold Fw 4150 OpenSmall Block Chevy versions of these intake manifolds are engineered specifically to port match fit RHS? Small Block Chevy cylinder heads. Additionally, these manifolds are the only ones designed with a 4150 flange and bolt machining to fit all versions of Small Block Chevy cylinder heads, including classic originals, Vortec GM heads and late model perimeter corner vertical bolt style crate engine heads. They provide the power and strong torque curve