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Chevy Small-Block v-8
Vortec Bowtie CYLINDER Heads
Vortec Bowtie cylinder heads are the most powerful cast-iron
heads offered by GM Performance Parts. These upgraded production
cylinder heads are ideal for 400-450 horsepower street and
racing (great for circle track applications) engines. Vortec Bowtie
cylinder heads come with bigger valves, a thicker deck surface and
66cc combustion chambers. The heads provide outstanding low-lift
flow numbers (the more air you flow, the more potential power)
and Fast Burn performance all in an affordable, cast-iron head.
Vortec Bowtie Cylinder Head Technical Notes:
• Cast-iron small runner or large runner cylinder heads 1
• 66cc combustion chambers
• 0.450" deck thickness
• Hardened exhaust valve seats
• Machined for 2.00"/1.55" valves
• Maximum 0.530" valve lift (without modifications)
• Straight spark plug design
• No heat risers
• Drilled and tapped for 7/16-14 screw-in studs
• Dual bolt patterns for Vortec and early style intake manifolds
(early model P/N 10051103; Vortec intakes P/N 12366573,
12496820, 12496821, 12496822 or 12499371)
• Use intake gasket P/N 12529094 for Vortec intakes or dual
pattern intake gasket P/N 12497760 for early model intakes or
Vortec design intake manifolds
• Dual bolt patterns for perimeter style and center-bolt valve
covers
• Vortec intake manifold three-step torque specs: 2 lb-ft; 9 lb-ft;
11 lb-ft
A. 25534421
Small Port Vortec Bowtie Cylinder Head Assembly
• Completely assembled, ready to bolt on
• 185cc intake ports
• 65cc exhaust ports
• Use Fel-Pro ® P/N 1470 exhaust gasket
• Bare head P/N 25534351, available separately
25534446
Large Port Vortec Bowtie Head Assembly
(not shown)
• Completely assembled, ready to bolt-on
• Improved air flow (281 cfm @ 0.600")
• 225cc intake ports
• 77cc exhaust ports
• 65cc combustion chambers
• Use Fel-Pro ® P/N 1470 exhaust gasket (minor trimming
may be necessary)
• Bare head P/N 25534445, available separately
These heads are assembled with the following components:
12363757 Intake Valves 10212808 Valve Spring Retainers
12363758 Exhaust Valves 10212810 Valve Stem Seals
12551483 Valve Springs 24503856 Valve Locks
12552126 3/8" Rocker Studs
A
A
A
Small and Large Port Vortec Bowtie Heads (intake). Bare head shown.
Small Port Vortec Bowtie Head (exhaust). Bare head shown.
Small Port Vortec Bowtie Head (chamber).
ZZ4 Aluminum Cylinder Head Assembly (exhaust)
ZZ4 Aluminum Cylinder Head Assembly (combustion chamber)
LT4 Aluminum Cylinder Head Assembly (intake)
LT4 Aluminum Cylinder Head Assembly (exhaust)
B
B
C
C
The ZZ4 Aluminum Head
The revolutionary lightweight ZZ4 aluminum cylinder head was a
key component of the highly successful Corvette L98 Small-Block
V-8 engine (1985-1990). GM Performance Parts offers that same
cylinder head as a complete assembly, with D-shaped exhaust
ports 1 (they increase post-combustion scavenging for increased
power), high-velocity exhaust runners and centrally located spark
plugs 2 that improve air/fuel mixture burn efficiency for increased
power potential. The ZZ4 aluminum cylinder head is ideal for a
great variety of engine applications.
B. 12556463
ZZ4 Aluminum Cylinder Head Assembly
• Aluminum performance head—used on ZZ4 engines
• Completely assembled with 1.94"/1.50" valves
• 163cc intake port
• 58cc combustion chamber
• No heat riser
• Angled spark plugs (5/8" hex, 3/4" reach, tapered plugs)
• 1.48" Valve spring seat diameter
• Screw-in studs (3/8" top, 7/16" bottom)
• Use head gaskets with stainless steel fire rings
• Raised, machined rocker rails
• Raised exhaust ports .100", requires Fel-Pro ® gasket
P/N 1470
• Use rail type rockers P/N 10089648, or kit
P/N 12370838 (roller rockers!)
• Casting P/N 10088113
This head is assembled with the following components:
12550909 Exhaust Valves 10212808 Valve Spring Retainers
10241743 Intake Valves 10212810 Intake Valve Stem Seals
12551483 Valve Springs 10212870 Exhaust Valve Stem Seals
10212809 Valve Spring Shims 24503856 Valve Locks
12552126 3/8" Rocker Studs
The LT4 Aluminum Head
The LT4 aluminum cylinder head represents another benchmark
in Chevrolet high performance engine technology. This premium
quality aluminum cylinder head is designed for use on 1992-andnewer
LT1 and LT4 Small-Block engines with reverse-flow cooling
systems. LT4 aluminum cylinder heads are key components of any
contemporary high horsepower GM Small-Block engine buildup.
C. 12363287
LT4 Aluminum Cylinder Head Assembly
• Aluminum performance head
• Can only be used on 1992–newer LT1 and LT4 engines
• Completely assembled with 2.00"/1.55" valves
• 195cc intake port
• 54.4cc combustion chamber
• No heat riser
• Angled spark plugs (5/8" hex, 3/8" reach, tapered plugs)
• 1.48" Valve spring seat diameter
• Screw-in studs (3/8" top, 7/16" bottom)
• Use head gaskets with stainless steel fire rings
• Raised, machined rocker rails
• Raised exhaust ports .100", requires Fel-Pro ® gasket
P/N 1470
• Use rail type rockers P/N 10089648, or kit
P/N 12370838 (roller rockers!)
This head is assembled with the following components:
12555331 Intake Valves 10212808 Valve Spring Retainers
12551313 Exhaust Valves 10212810 Valve Stem Seals
12551483 Valve Springs 10212809 Valve Spring Shims
12552126 3/8" Rocker Studs 24503856 Valve Locks
Chevy small-block v-8
1
D-shaped exhaust ports increase the scavenging of the exhaust after combustion.
The quicker you can get the exhaust out, the quicker you can get the air/fuel
mixture into the combustion chamber. And, that equals big power!
1
Larger intake and exhaust ports allow for more volume of air to pass through the
engine. The more air you flow, the more power you can make.
B ZZ4 Aluminum Cylinder Head Assembly (intake) LT4 Aluminum Cylinder Head Assembly (combustion chamber) C
2
Centrally-located spark plugs allow for a more efficient flame front and air/fuel
mixture burn during combustion, greatly increasing the power potential of the
cylinder head.
148 Buy online at www.gmperformanceparts.com
Additional components required
for installation. See page 155.
Available for purchase online at
gmperformanceparts.com
149