Page 242 of GM Performance Parts 2006 Catalog by GM Parts Direct

NOTE: 18 Aluminum Cylinder Head (exhaust) A 18 Aluminum Cylinder Head (top/intake) A 240 18 Aluminum Cylinder Head (combustion chamber) A V-6-90 CYLINDER HEADS A. 10134359 18 Aluminum Cylinder Head Low-port 18 aluminum cylinder head for maximum-effort competition engines. These heads offer significant improvements over conventional head designs with 18 valve angles (vs. older 23 angles) and 43 cc combustion chambers. Spark plug holes are centrally located, valve centerlines are relocated, and the exhaust ports are high-flow. Head face has an extra 0.080" of material for 9.1:1 compression. Up to 2.20" intake valves can be used. Shallow wedge-shaped combustion chambers allow builders to achieve high compression ratios with small piston domes. Heads do not include valve seats or guides. Aftermarket shaft-mounted rocker arm assemblies and pushrods are required. Piston domes and valve pockets must be matched to the revised combustion chamber design. 12480009 18 Aluminum Cylinder Head (not shown) Low-port 18 aluminum cylinder head for competition engines that is identical to P/N 10134359, except that it has a new design intake port for Daytona Dash Racing Series. 10134394 Splayed Valve Bowtie Cylinder Head (not shown) The splayed-valve Bowtie cylinder head with 45 cc chambers represents a radical change from conventional V-6 90 cylinder head designs. GM engineers adopted the big-block Chevrolet V-8s free-breathing valve layout to the Chevrolet V-6. The intake and exhaust valves are inclined in two axes relative to the cylinder bore centerline. This compound valve angle moves the valve head away from the cylinder wall as the valve opens. This design minimizes valve shrouding and promotes airflow at high lift. This cylinder head uses rocker arm mounting bar P/N 10134395, intake manifold gasket P/N 10185004 and rocker cover gasket P/N 10185008. Also required are aftermarket manifolds, valvetrain components and build your own valve covers. 90 V-6 CYLINDER HEADS QUICK REFERENCE CHART Part Casting Port Port Valve Chbr Int Exh Plug Heat Rocker Number Description Number Mat'l Size Type Angle CC's Vlv Vlv Type Riser Stud Notes 10134359 18 V-6 12480009 Aluminum 215 Raised 18 43 2.15 1.62 Angled No Shaft No seats/guides 12480009 18 V-6 12480009 Aluminum 215 Raised 18 43 2.15 1.62 Angled No Shaft As cast ports 10134394 Splayed valve V-6 Aluminum 240 Splayed Splayed 45 2.20 1.65 Angled No Shaft As cast ports CHEVY V-6 60 AND 90

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