The cylinder heads for the Vortec 5.7-liter (350-cubic-inch) small block Chevy (SBC) engine were used on GM trucks and vans beginning in 1996. GM engineers designed a cylinder head that became popular with performance enthusiasts.
Vortec heads are made from cast iron and incorporate an intake port shape designed to promote "swirl" or turbulence. They share many similarities with older heads, but have intake ports that are slightly larger--170cc versus 160cc. As with many older head designs, 1.94-inch and 1.50-inch intake and exhaust valves are used. An eight-bolt intake manifold pattern replaces the conventional 12-bolt pattern.
The shape of the Vortec intake port and 64cc combustion chamber provides an increased velocity of the incoming air-fuel mixture, producing a swirl once the mixture gets inside the combustion chamber. This promotes a more efficient ignition of the fuel and results in greater torque and horsepower.
Valve Springs/Valve CoversOne restriction of the 350 is the lack of valve guide boss-to-retainer clearance when using camshafts and valve springs with valve lift greater than stock. However, that can be remedied with some simple machine work. In addition to the eight-bolt manifold pattern, the Vortec heads have center-bolt valve covers rather than the four perimeter bolts used on older heads.
