GM Performance 12363390 - GM Performance Parts BB-Chevy Cylinder Heads
GM Performance #809-12363390BB-Chevy Oval Port Aluminum Head 2.25" Valves |
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GM Performance 12363390 - GM Performance Parts BB-Chevy Cylinder Heads Details
This head is identical to 809-12363399, except it has 2.25" stainless steel intake valves, and 1.88" stainless steel exhaust valves with 11/32 stems. It also includes high performance valve springs, valve spring caps, keys and valve stem seals. These heads are designed for high horsepower 396, 427, 454, and 502 engines. Technical Notes: For 502ci engines, use head gasket kit 809-12363411 and no sealant on the head bolt. For all big-block engines, use intake manifold gasket kit 809-12366985, with intake bolt kit 809-12367959, and cylinder head bolt kit 809-12367779. Use the following components for service: 809-12366987 Intake Valve 2.25"; 809-1366988 Exhaust Valve 1.88"; 809-12462970 Valve Spring; 809-12366990 Valve Spring Retainer; 809-3875916 Valve Spring Shim (Requires 2); 809-12366992 Valve Lock; 809-12495690 Oil Seal.
Valve Spring Specs:
Outside Diameter: 1.514''
Install Height: 1.940''
Seat Pressure: 140 @ 1.940''
Coil Bind: 1.200''
Spring Rate: 325 lbs./in.
GM Performance Parts service replacement cylinder heads are direct replacements on most 1990-and-later GM Big-Block 454-cubic-inch and 502-cubic-inch engines. These brand-new cylinder heads meet GM's stringent quality standards and provide excellent service and durability not found in used cylinder heads. The cylinder heads have rectangular intake ports1, which are larger in volume and designed to enhance high-rpm horsepower. These service replacement heads are ideal for Big-Block street machines that also see drag strip action.
