LT4 Head Data

The following related components are recommended when installing GMPerformance Parts Corvette aluminum cylinder head assemblies:
Part Number Description
12555269 Stamped steel rocker cover 10229162 Corvette screw-in oil filler cap 12342056 Chrome screw in oil cap w/GM logo 12338092 Valve cover hold-down bolts (8 required) 14094717 Hold-down bolt washers (8 required) 14088793 Hold-down bolt gaskets (8 required) 14088564 Neoprene rocker cover gasket 12557236 Composition head gasket, .051" thick 12495499 Head Bolt Kit 12495490 Rocker Arm Kit

12363287 — LT4 Design Aluminum Cylinder Head This aluminum LT4 design head is the same as the 1996 production head except it has the LT1 rocker stud P/N 12552126 installed. This head has light weight 2.00" intake and 1.55" exhaust valves installed in this assembly. These heads can only be used on 1992 and later LT1 and LT4 engines. NOTE: This head assembly includes the following items, intake valve P/N 12555331, exhaust valve P/N 12551313, valve spring P/N 12551483, valve cap P/N 10212808, seal P/N 10212810, key P/N 24503856, stud P/N 12552126, and shim P/N 10212809.
P/N	DESC	CSTNG NUMBER	MAT'L	INTAKE RUNNER VOLUME (cc)	COMB CHAMBER VOLUME (cc)	VALVE DIAMETER	SPRK PLUGS	HEAT RISERS	NOTES
12363287	LT4 SERVICE ONLY	NA	ALUM	195	54.4	I: 2.00" E: 1.55"	Angled	No	For LT1 or LT4 usage only

GROUP 0.296 INTAKE VALVES

12551313 — Exhaust Valve 1.55" Diameter
These 1.55" exhaust valves are used in the 1996 350 LT4 Corvette.

12555331 — Intake Valve 2.00" Diameter
These 2.00" intake valves are used in the 1996 350 LT4 Corvette.

VALVE SPRINGS — SMALL-BLOCK V8 AND V6/90°QUICK REFERENCE CHART

PN DESC OUTSIDE DIAMETER PRESSSURE AT INTALLED HEIGHT SOLID HEIGHT AVERAGE RATE (# per in) RETAINER PN VALVE SEAL KIT NOTES

10206040 Single Spring 1.30" 85# @ 1.78" 1.26" 373 10168424 NA LT1 production Corvette
engine.

12551483 Single Spring 1.32" 101# @ 1.78" 1.22" 332 10212808 NA 1996 LT4 Corvette and ZZ4 engines.

10212810 — Valve Stem Seal LT4
These valve stem seals are used on 1996 350 LT4 engines and special performance LT4 design service heads.

10212809 —Valve Spring Shim LT4
These valve spring shims are used on 1996 LT4 Corvette engines as well as the special LT service-only heads P/N 12363287. These are light weight caps Technical Note: Use with spring P/N 12551483.

10168424 — Valve Spring Cap
Used on 1992-93 Corvette LT1 engines. This lightweight cap is to be used with spring P/N 10206040.

12495492 — Valve Spring Cap Kit, LT4
This valve spring cap kit which includes 16 of P/N 10212808 caps, is used on all 5.7L LT4 engines. These are light weight caps to be used with valve spring kit P/N 12495494, and key kit P/N 12495503.

10212808 — Valve Spring Cap LT4 - ZZ4
These valve spring caps are used on 1996 LT4 Corvette ZZ4 engines as well as the special service only heads P/N 12556463. These are light weight caps.
Technical Note: Use with spring P/N 12551483.

			GROUP 0.296 INTAKE VALVES
			12551313 — Exhaust Valve 1.55" Diameter These 1.55" exhaust valves are used in the 1996 350 LT4 Corvette.
			12555331 — Intake Valve 2.00" Diameter These 2.00" intake valves are used in the 1996 350 LT4 Corvette.
			VALVE SPRINGS — SMALL-BLOCK V8 AND V6/90°QUICK REFERENCE CHART
PN	DESC	OUTSIDE DIAMETER	PRESSSURE AT INTALLED HEIGHT	SOLID HEIGHT	AVERAGE RATE (# per in)	RETAINER PN	VALVE SEAL KIT	NOTES
10206040	Single Spring	1.30"	85# @ 1.78"	1.26"	373	10168424	NA	LT1 production Corvette engine.
12551483	Single Spring	1.32"	101# @ 1.78"	1.22"	332	10212808	NA	1996 LT4 Corvette and ZZ4 engines.
			10212810 — Valve Stem Seal LT4 These valve stem seals are used on 1996 350 LT4 engines and special performance LT4 design service heads.

			10212809 —Valve Spring Shim LT4 These valve spring shims are used on 1996 LT4 Corvette engines as well as the special LT service-only heads P/N 12363287. These are light weight caps Technical Note: Use with spring P/N 12551483.

			10168424 — Valve Spring Cap Used on 1992-93 Corvette LT1 engines. This lightweight cap is to be used with spring P/N 10206040.

			12495492 — Valve Spring Cap Kit, LT4 This valve spring cap kit which includes 16 of P/N 10212808 caps, is used on all 5.7L LT4 engines. These are light weight caps to be used with valve spring kit P/N 12495494, and key kit P/N 12495503.

			10212808 — Valve Spring Cap LT4 - ZZ4 These valve spring caps are used on 1996 LT4 Corvette ZZ4 engines as well as the special service only heads P/N 12556463. These are light weight caps. Technical Note: Use with spring P/N 12551483.