Chevrolet Performance Bowtie Aluminum Cylinder Heads

Chevrolet Performance Bowtie aluminum cylinder heads offer an ideal combination of street drivability and drag-strip performance. These aluminum cylinder heads provide a broad power range with ample low-end torque, along with excellent throttle response, good mid-range torque and enough top-end power to beat your competitors to the finish line. Designed for high performance applications, the Bowtie Street cylinder heads are manufactured to precise machining tolerances, with thick deck surfaces and high-velocity airflow passages. They are available in either rectangular or oval intake port configurations. The rectangular intake ports are larger in volume and have been designed to enhance high-rpm horsepower, which makes them best for vehicles that see frequent drag-strip action. Cylinder heads with oval intake ports are smaller in volume and designed for greater low-rpm torque, therefore they're best for street applications, where lots of bottom end, off-the-line power is desired. Bowtie Street Cylinder Head Technical Notes: * Made from 356-T6 aluminum * Available in rectangular or oval-port designs * Will work on Mark IV and Gen V, VI blocks * 9/16 in. thick decks * As-cast intake and exhaust ports * No heat risers * 1.55 in. valve spring seat diameter * Heli-coiled 7/16 in. screw-in rocker stud holes * Designed for use with 3/8 in. pushrods * Use intake gasket P/N 12366985 and bolt kit P/N 12367959 * Use head gasket P/N 12363414 for bores to 4.370 in. and P/N 12363413 for bores 4.470 in. to 4.540 in. (Mark IV) * Use head gasket P/N 12363412 for bores to 4.370 in. and P/N 12363411 for bores 4.470 in. to 4.540 in. (Gen V, VI) * Use head bolt kit P/N 12367779 Bowtie Oval-Port Aluminum Cylinder Head Assembly: * Completely assembled with 2.250 in./1.880 in. 11/32 in. stem valves * 290cc oval intake ports * 110cc exhaust ports * 110cc combustion chambers Cylinder head is assembled with the following components: * 2.190 in. intake valves * Valve spring retainers * 1.880 in. exhaust valves * Valve locks * Valve springs * Valve seals * Valve spring shims * Rocker arm studs * Pushrod guideplates Show Less