High-rise Chevrolet Performance oval port dual plane intake manifolds are the latest in dual plane design thinking and technology. They're intended for all big block Chevrolet 396-502 c.i.d. engines with either current oval port aluminum heads or 1975 and earlier large oval port iron heads. They're set up for a single spread-bore 4-barrel and have dual bolt patterns on the carburetor flange. There is no provision for hot-air chokes, and they will not fit some Corvettes with limited hood clearance.