Chevy Small Block V8
SERVICE REPLACEMENT HEADS These heads are designed to be direct replacements for the heads that came standard on
most GM V-8 small-block engines from 1987–newer. They are perfect for replacing worn or damaged heads, and they are built with the same high quality standards that you have come to expect from GM. Service Replacement Head Technical Note:
Cast iron cylinder head
Straight spark plugs
Uses 1.94"/1.50" valves
No heat risers 93438649
Cylinder Head Assembly With Valves For 290 HP (not shown)
This cast iron cylinder head services 350/290 hp crate engine as well as Goodwrench base 350 P/N 10067353.
The bare head for this assembly is P/N 93438648.
76cc combustion chamber
Standard ‘old style’ 6-bolt intake pattern This head is assembled with the following components:
14075641 Intake Valves 10241744 Intake Spring Retainer
10241743 Exhaust valves 14042575 Exhaust Spring Retainer
94666580 Valve Springs 10212810 Intake Seals
24503856 Valve Locks 12564852 Exhaust Seals VORTEC CYLINDER HEADS One of America’s favorite high performance cast iron small-block cylinder head offers big power at an incredible value. The modified combustion chambers and high velocity port technology offer impressive power gains at an affordable price. The Vortec head significantly outflows our non-Vortec service replacement head and offers a 20-40 horsepower increase over earlier cast iron heads. They will fit 1955-and-later small-block except for the LT1/LT4 and LS Family of engines. Take your small-block to the 350 horsepower level with a set of Vortec cylinder heads! (These heads require Vortec-specific intake manifolds.)
 A. 12558060
Cast Iron Vortec Cylinder Head Assembly
Completely assembled with 1.94”/1.50” valves
Uses bare head 12529093
64cc combustion chamber
Straight spark plugs
No heat risers
Requires Vortec specific intake manifold
Camshafts with more than 0.475" lift require machining valve guide bosses and checking valve seal to valve spring retainer clearance
Can be machined for 2.02"/1.60" valves
Rocker arm studs can be pinned or drilled
Valve spring seat diameter is 1.48"
This head is assembled with the following components:
10241743 Intake Valves 10241744 Valve Spring Retainer
12550909 Exhaust valves 10212810 Intake Seals
10212811 Valve Springs 12564852 Exhaust Seals
12564852 Valve Locks  THE PHASE 3 CAST IRON BOWTIE HEAD The Phase 3 Bowtie head was the first true cast iron performance head offered by GM Performance Parts. As such, it will outflow any production-style cast iron head. Intended for off -highway use only, the Phase 3 Bowtie head offers extra - thick castings for you to experiment with port modification. This head is designed for the all-out competitive racer who must run a production-style cast iron head.  B. 12480034
Phase 3 Cast Iron Bowtie Head
Cast iron Phase 3 Bowtie head
Extra-thick walls for porting
Machined for 2.02"/1.60" valves
Exhaust seats are induction hardened
Valve spring seat is machined for 1.50" competition springs
184cc intake runner
64cc combustion chamber
No heat riser
Angled spark plugs (5/8" hex, 3/8" reach, tapered plugs)
Requires early model intake manifolds
Valve spring seat is machined for 1.50" competition springs
Use P/N 12495497 screw-in studs for 3/8" rocker arms
Use P/N 3921912 screw- in studs for 7/16" rocker arms
Use P/N 3973418 guide plates for hardened pushrods 
VORTEC BOWTIE HEADS These are GM Performance Parts’ most powerful cast iron cylinder heads designed for street or racing applications in the 400–450 horsepower range. As an upgraded production head, they come with bigger valves, a thicker deck surface, and a 66cc combustion chamber, which offer tremendous low-lift flow numbers. They offer you Fast Burn performance in an affordable cast iron head that is often used for short-track racing applications.
 Vortec Head Technical Note:
Cast iron small runner or large runner heads1
66cc combustion chamber, .450" deck thickness
Straight spark plugs
No heat risers
Machined for 2.00"/1.55" valves
Hardened exhaust valve seats
0.530" max valve lift (without modifications)
Drilled and tapped for screw-in studs (7/16-14)
Dual bolt patterns for perimeter bolt and center bolt valve covers
Dual bolt patterns for both Vortec and early model intake manifolds (use early model P/N 10051103 or Vortec design
P/N 12366573, P/N 12496820, P/N 12496821, P/N 12496822, or P/N 12499371)
Use production intake gasket P/N 12529094 for Vortec intakes or dual bolt pattern intake gasket P/N 12497760 for either early model or Vortec design manifolds
Vortec logo (intake port roof), GM logo (intake port floors) & Bowtie logo (exhaust side) are cast-in
 A. 25534421
Small Port Vortec Bowtie Head Assembly
Completely assembled, ready to bolt-on
185cc intake port
65cc exhaust port
Uses Fel-Pro #1470 exhaust gasket
Bare head P/N 25534351 available separately
 B. 25534431
Large Port Vortec Bowtie Head Assembly
Completely assembled, ready to bolt-on
215cc intake port
84cc exhaust port
Uses Fel-Pro #1470 exhaust gasket, may require minor trimming
Bare head P/N 25534371 available separately
These heads are assembled with the following components:
25534407 Intake Valves 10212808 Valve Spring Retainers
25534408 Exhaust Valves 10212810 Valve Stem Seals
12551483 Valve Springs 12564852 Valve Locks
12552126 3/8" Rocker Studs
THE ZZ4 ALUMINUM HEAD The L98 Corvette small-block was a breakthrough in advanceddesign and efficiency largely because of the lightweight aluminum heads that were used on that engine. GM Performance Parts now offers you that same cylinder head in one complete assembly that features a D-shaped exhaust port2, high-velocity intake runners, and centrally-located spark plugs3. The applications are endless.  C. 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
Exhaust ports are raised .100", requires Fel-Pro gasket #1470
Use rail type rockers P/N 10089648, or kit
P/N 12370838 (roller rockers!) This head is assembled with the following components:
12550909 Intake Valves 10212808 Valve Spring Retainers
10241743 Exhaust Valves 460483 Intake Valve Stem Seals
12551483 Valve Springs 10147883 Exhaust Valve Stem Seals
10212809 Valve Spring Shims 12564852 Valve Locks
12552126 3/8" Rocker Studs THE LT4 ALUMINUM HEAD Like the L98 Corvette head, the LT4 casting ushered in the next generation of high-performance GM performance small-block. The LT4 head has the latest in GM Performance Parts technologies with all of our high-end quality materials. This head can only be used on 1992-and-newer LT1 and LT4 engines with the reversecoolant flow design. It makes a great starting point for you to build a high horsepower version of one of these engines.   A. 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, 3/4" 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
Exhaust ports are raised .100”, requires Fel-Pro gasket #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
ALUMINUM FAST BURN HEADS When it comes time to own the street, this is the head for you! GM Performance Parts has brought together all of our new technologies to create the ultimate 23-degree small-block GM cylinder head. Fast Burn technology maximizes combustion of the air/fuel mixture, resulting in higher cylinder pressures and more power production. The combustion chamber (62cc) is designed for flat top pistons, and the head requires no additional porting for optimum performance, so it provides maximum “out-of-the-box” performance. Recommended for any standard coolant flow 1955–2000 283–400 cubic inch small-block, the Fast Burn head helps us make 425 horsepower from our own ZZ383 crate engine !  B. 12464298
Aluminum Fast Burn Cylinder Head Assembly
CNC-machined aluminum performance head
Completely assembled with 2.00"/1.55" valves
210cc intake port, roof raised .240"
78cc D-shaped exhaust ports, raised .200", requires Fel-Pro gasket #1470 (may require minor trimming)
62cc combustion chamber, .400" thick deck (can be milled safely .060")
No heat riser
Angled spark plugs (5/8" hex, 3/4" reach, tapered plugs)
1.48" Valve spring seat diameter
Use head gaskets with stainless steel fire rings
Raised, machined rocker rails
0.530" max valve lift (without modifications)
Screw-in studs, (3/8" top, 7/16" bottom)
Dual bolt patterns for perimeter bolt and center bolt valve covers
Dual bolt patterns for both Vortec and early model intake manifolds
Use production intake gasket P/N 12529094 for Vortec intakes or dual bolt pattern intake gasket P/N 12497760 for either early model or Vortec design manifolds (Fel-Pro #1289 and #1207 may be used)
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 LATE MODEL ALUMINUM SHORT TRACK AND NHRA COMP ELIMINATOR RACING HEADS GM Performance Parts has been making big power for decades! Now, the same technology that dominates NASCAR and the NHRA is available to the general public for use in your Late Model Saturday night racecar or your serious drag car effort! We’ve designed an entire family of high performance in-line valve cylinder heads that are ready to take you to the winner’s circle. These heads come with thicker deck material and thicker manifold flange areas, powerful combustion chambers and high velocity air passages. Drag racers in NHRA’s Competition Eliminator want big compression, lots of rpm, and a cylinder head that delivers maximum power at the crack of the throttle. Coupled with the correct valve train, intake, and short block, these Racing Heads are exactly what small displacement drag racers have been looking for. The GM Performance Parts engineers have dramatically altered the valve architecture in this head to improve airflow and maximize efficiency. We’ve also left some of these heads unported, so that your favorite aluminum artist can go to work on them to perfect your given application. Buy a set of these heads from GM Performance Parts, and the only thing you’ll have to worry about is the driving!
Aluminum Racing Head Technical Note:
355-T7 Aluminum Competition cylinder heads
Extra thick decks for angle milling or heavy flat milling
Recommended for 4.000"–4.155" cylinder bore
Extra material around ports for professional porting
Revised location angled spark plugs, (14mm, 5/8" hex, 3/4" reach, gasketed plugs)
Raised & revised location intake and exhaust ports for superior airflow above .600" valve lift
Longer than stock valves required
Modified valve angles (not production 23)
Designed for aftermarket shaft-mount rocker systems
Perimeter bolt pattern valve covers required
Specific 18/15 intake manifold bolt patterns
Recommended intakes: P/N 24502481, P/N 24502487, P/N 24502579 or P/N 24502653 (with valley plate P/N 24502654)
Intake manifold gasket P/N 10185007  24502580 Semi-Finished 18 Cylinder Head
Fully machined, semi-finished,
no seats or guides
Non-CNC ports and combustion chamber are “as-cast”
60cc “as-cast” combustion chambers
Designed for up to 2.20"/1.625" valves
215cc “as-cast” intake ports
.080" extra material on deck face, and .055" on intake face
 24502615 Semi-Finished 15 Cylinder Head
Fully machined, semi-finished, no seats or guides
Non-CNC ported, ports and combustion chamber are “as-cast”
Great head for NHRA Comp-Eliminator, both V-8 and 4-cylinder applications!
Casting has been “rolled” 2, Valve-guides are also tipped 1
210cc “as-cast” intake ports
35–37cc “as-cast” combustion chamber
Capable of over 900 horsepower
Multi-NHRA world records
SPLAYED-VALVE ALUMINUM RACE HEAD4 Departing from the in-line valve head, our splayed-valve castings have a 0.240" minimum port wall thickness so your favorite head porting expert can perform extensive modifications for greater airflow. Intake valves are angled 16 to the deck surface and tilted (splayed) 4. Exhaust valve angles are 11, with a 4 tilt. This is an extremely aggressive, all -out competition race head designed to make the absolute maximum power from your small-block Chevy with no regard to streetability. Our NHRA Competition Eliminator customers routinely make over 1000 horsepower (naturally aspirated) with this cylinder head!
 Aluminum Splayed Valve Race Head Technical Note:
355-T7 Aluminum Competition cylinder heads
No seats or guides
Extra thick decks for angle milling or heavy flat milling
45cc “as-cast” combustion chambers
.240" Extra material around ports for professional porting
Revised location angled spark plugs, (14mm, 5/8" hex, 3/4" reach, gasketed plugs)
Completely revised intake & exhaust ports offer the ultimate in airflow potential
Designed for longer than stock 2.20" & 1.65" valves
Modified valve angles, 16 x 4 intake, and 11 x 4 exhaust
Valve Spring pads accommodate 1.625" diameter valve springs
All pistons have same orientation
Designed for aftermarket shaft-mount rocker systems
Valve Cover P/N 10185045 and valve cover gaskets P/N 10185043 required P/N 10185042 intake manifold gasket required
Custom fabricated intake manifold required
12480146
Rough-Machined Splayed-Valve Aluminum Cylinder Head (not shown)
Main surfaces are machined, exhaust bolt pattern is machined
Head bolt & dowel holes, intake bolt holes, spark plug holes & pushrod holes are not machined
Valve guides valve seats, valve spring seats & rocker stands are not machined
Valve locations and angles may be relocated
240cc “as-cast” intake ports
78cc “as-cast” exhaust ports
45cc “as-cast” combustion chambers 12480147
Semi-Machined Splayed-Valve Aluminum Cylinder Head (not shown)
Main surfaces are machined, exhaust bolt pattern, valve guides and spark plug holes are machined
Head bolt holes, dowel holes, intake bolt holes, pushrod holes are not machined
Valve seats, spring seats & rocker stands are not machined
240cc “as-cast” intake ports
78cc “as-cast” exhaust ports
45cc “as-cast” combustion chambers
Same casting as P/N 12480146  A. 24502517
Splayed-Valve Aluminum Cylinder Head
Semi-machined aluminum race head
240cc “as-cast” intake ports
78cc “as-cast” exhaust ports
45cc “as-cast” combustion chambers
Same casting as P/N 12480146
A. 12480153
Splayed-Valve R0X Aluminum Cylinder Head
Semi-machined aluminum race head
Great for NHRA competition with dual carburetors
As cast ports and combustion chambers for professional finishing
Machined for 4.500" bore center R0X cylinder block P/N 25534352
Special larger head-bolt pattern, 3/8" fasteners, 19 holes
240cc “as-cast Peanut” intake ports 
78cc “as-cast Peanut” exhaust ports
40cc “as-cast” combustion chambers 88958684
Rough Machined Splayed-Valve R0X Aluminum Cylinder Head (not shown)
Main surfaces are machined and exhaust bolt pattern is machined
No valve guide or valve seat machining SB2.2 NASCAR RACE HEADS The SB2 NASCAR racing head was first designed to improve durability, simplify preparation procedures, and reduce the overall cost of building and maintaining a small-block racing engine. It has “mirror” design intake ports, and all eight ports are angled toward the center of the engine, making this a perfect choice for single four-barrel applications. Spark plug holes were moved toward the bore center for greater combustion efficiency. This head is designed for aftermarket shaft-mounted rocker arms, and valve spring pads are large enough to use 1.625" springs. The combustion chambers are 48cc, which allow a 12.1:1 compression ratio with flat-top pistons. The head is machined for standard 1/2" valve guides.
Aluminum SB2.2 NASCAR Race Head Technical Note:
355-T7 X-rayed and “Hipped” Aluminum Competition cylinder heads
Extra thick decks for heavy flat milling
Combustion chambers are very small, shallow & wedge shaped
Extra material around ports for professional porting Revised location angled spark plugs, (14mm, 5/8" hex, 3/4" reach, gasketed plugs)
“Mirror” design intake ports are angled toward center of engine for single 4-barrel carb applications
Designed for 2.15" & 1.625" valves, longer than stock valves required
Valve Spring pads accommodate 1.625" diameter valve springs
Modified valve angles, 11 x 4 intake, and 8 x 0 exhaust
Requires left and right-hand pistons
Precision T-washers installed in all (4) center head bolt bosses
Designed for aftermarket shaft-mount rocker systems
Valve cover P/N 12480006 or P/N 12480012 required
Replacement AN-08 intake port plugs are available as P/N 12480171  B. 12480011
Semi-finished SB2.2 Aluminum Cylinder Head
Aluminum NASCAR accepted head
Bare head, no seats or guides installed
Standard .500" guide holes
As cast ”Peanut” ports
48cc “as cast” combustion chamber
 12480129
Semi-finished SB2.2 Aluminum Cylinder Head
Aluminum NASCAR accepted head
Bare head, no seats or guides
Reduced size .375" diameter guide holes
As cast ”Peanut” ports
48cc “as-cast” combustion chamber
 C. 88958667
Semi-finished SB2.2 Design R0X Aluminum Cylinder Head
Fully CNC-machined aluminum race head
Has cast ports and combustion chambers for professional finishing
Machined for 4.500" bore center R0X cylinder block P/N 25534453
Special spread head-bolt pattern, 3/8" fasteners, 19 holes
Machined with additional .070" material on deck face.
Valve centerlines moved apart .100 for additional valve clearance and larger valves
Valve angles are 11 x 4 intake, and 7 x 2 exhaust
Exhaust port positions are slightly reoriented, but same bolt pattern as standard SB2.2
As cast ”Peanut” intake ports
As cast ”Peanut” exhaust ports
28cc “as-cast” combustion chambers
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