18° Magnum
AFR’s new 457cc 18° Big Block Chevy cylinder heads are our best performing highest-flowing heads in our BB Chevy lineup. They come standard with stainless steel 2.400 intake valves and 1.800 exhaust valves.
The intake port is raised .500 with the valves rolled to 18° resulting in unparalleled under the curve flow numbers..... don’t be fooled by just peak flow numbers. The combustion chamber come in at 90cc. This head is ideal for 540CI or larger race engines. This head requires specific pistons, valves covers, shaft mount rockers and readily available intake manifolds. AFR offers a wide range of options and upgrades for this head like titanium valves and Copper seats.
| Basic Package Components | |
| 100% CNC Ported Intake Ports, Exhaust Ports, & Combustion Chamber | |
|
Competition 5-angle Valve Job |
|
| 11/32" Bead Lock Stainless Steel Intake Valve, 2.400" X 6.035" O.A.L. 50° Seat | |
| 11/32" Bead Lock Stainless Steel Exhaust Valve, 1.800" X 5.935" O.A.L. 55° Seat | |
| PAC Racing #1258 1.645” OD Solid Roller Triple Spring, 350 lbs. on seat, .950” maximum lift Max RPM 8300 to 8500 | |
| 10° Titanium Retainer 1.500" O.D X1.180"I.D X .765" I.D | |
| 10° 11/32" Bead Lock Valve Keepers with recess lashcaps | |
| 11/32" Viton Valve Seals | |
| Hardened Spring Cup 1.740 O.D X 1.677 I.D X .570 | |
| Intake Valve Seats 2.500" O.D X 2.000" I.D X .375" Deep | |
| Exhaust Valve Seats 1.900" O.D X 1.400" I.D X .375" Deep | |
| 11/32" Bronze Valve Guides .502" O.D X 2.700 O.A.L. | |
| 11/32" Exhaust Bronze Valve Guides .502" O.D x 2.25" O.A.L | |
| 457cc BBC | |||||||||
| .200 | .300 | .400 | .500 | .600 | .700 | .800 | .900 | 1.000 | |
| Int | 161 | 254 | 331 | 389 | 439 | 479 | 492 | 495 | 498 |
| Exh | 134 | 201 | 251 | 286 | 305 | 315 | 332 | 337 | 342 |
Test conducted at 28" of water (pressure) on Superflow 1020
Bore Size: 4.625", 3/4" intake radius plate, 2 1/8" curved pipe exhaust
| Specifications & Features: | |
| Material |
A356 Aluminum
|
| Intake Port Volume |
457cc
|
| Intake Port Dimension |
2.490" H X 1.750" W X 1/2" Radius
|
| Intake Port Location |
.500" Raised
|
| Exhaust Port Volume |
143cc
|
| Exhaust Port Dimension |
1.850"H x 2.090" W
|
| Exhaust Port Location |
.450" Raised
|
| Combustion Chamber Size |
90cc
|
| Valve Cover Bolt Pattern |
Standard
|
| Valve Angle |
18°/4° Int, 11°/4° Exh
|
| Valve Spring Pocket Diameter |
1.750" O.D
|
| Max Valve Spring Pocket Machining |
1.750" O.D
|
| Warning: Do not machine spring pad any deeper | |
| Deck Thickness |
.750"
|
| Minimum Bore Diameter |
4.600"
|
| Flat Mill |
.005" per cc
|
| Angle Mill |
.0066" per cc
|
| Note:Angle mills might require a .120" Thick intake gasket. | |
| Minimum Cross Sectional Area |
3.699 sq. in.
|
| Spark Plug Dimensions |
14mm x .750" w/ Tapered Seat
|
|
CARB Status:This product is not legal for sale or use on emission-controlled vehicles and intended for dedicated race vehicles only. |
|
| Recommended Components: | |
| Intake Port Gasket | |
| Important: Do not use your AFR gasket as a template to port match your intake manifold as one AFR gasket is used for many AFR runner volumes. | |
| Exhaust Port Gasket | |
| Head Gasket, Fel Pro #1057 |
Fel Pro #1057
|
| Head Gasket, Cometic C5434 |
Cometic C5434
|
| Head Studs, ARP 135-4305 | |
| 1.8 Shaft Mount Rocker Arms T&D |
#3160
|
| 1.8 Shaft Mount Rocker Arms Crower |
|
| 1.8 Shaft Mount Rocker Arms Jesel |
#KPS-441172
|
| Suggested Manifold | |
| Suggested Manifold | |
| Spark Plug Starting Range |
Autolite 3932
|
| Distributor Standard Deck |
MSD #84697 or #8489
|
| Distributor Tall Deck |
MSD #85561 or #8547
|
| Valve Cover | |
| Valve Cover Gasket | |
AFR’s new 457cc 18° Big Block Chevy cylinder heads are our best performing highest-flowing heads in our BB Chevy lineup. They come standard with stainless steel 2.400 intake valves and 1.800 exhaust valves.
The intake port is raised .500 with the valves rolled to 18° resulting in unparalleled under the curve flow numbers..... don’t be fooled by just peak flow numbers. The combustion chamber come in at 90cc. This head is ideal for 540CI or larger race engines. This head requires specific pistons, valves covers, shaft mount rockers and readily available intake manifolds. AFR offers a wide range of options and upgrades for this head like titanium valves and Copper seats.
| Basic Package Components | |
| 100% CNC Ported Intake Ports, Exhaust Ports, & Combustion Chamber | |
|
Competition 5-angle Valve Job |
|
| 11/32" Bead Lock Stainless Steel Intake Valve, 2.400" X 6.035" O.A.L. 50° Seat | |
| 11/32" Bead Lock Stainless Steel Exhaust Valve, 1.800" X 5.935" O.A.L. 55° Seat | |
| PAC Racing #1258 1.645” OD Solid Roller Triple Spring, 350 lbs. on seat, .950” maximum lift Max RPM 8300 to 8500 | |
| 10° Titanium Retainer 1.500" O.D X1.180"I.D X .765" I.D | |
| 10° 11/32" Bead Lock Valve Keepers with recess lashcaps | |
| 11/32" Viton Valve Seals | |
| Hardened Spring Cup 1.740 O.D X 1.677 I.D X .570 | |
| Intake Valve Seats 2.500" O.D X 2.000" I.D X .375" Deep | |
| Exhaust Valve Seats 1.900" O.D X 1.400" I.D X .375" Deep | |
| 11/32" Bronze Valve Guides .502" O.D X 2.700 O.A.L. | |
| 11/32" Exhaust Bronze Valve Guides .502" O.D x 2.25" O.A.L | |
| 457cc BBC | |||||||||
| .200 | .300 | .400 | .500 | .600 | .700 | .800 | .900 | 1.000 | |
| Int | 161 | 254 | 331 | 389 | 439 | 479 | 492 | 495 | 498 |
| Exh | 134 | 201 | 251 | 286 | 305 | 315 | 332 | 337 | 342 |
Test conducted at 28" of water (pressure) on Superflow 1020
Bore Size: 4.625", 3/4" intake radius plate, 2 1/8" curved pipe exhaust
| Specifications & Features: | |
| Material |
A356 Aluminum
|
| Intake Port Volume |
457cc
|
| Intake Port Dimension |
2.490" H X 1.750" W X 1/2" Radius
|
| Intake Port Location |
.500" Raised
|
| Exhaust Port Volume |
143cc
|
| Exhaust Port Dimension |
1.850"H x 2.090" W
|
| Exhaust Port Location |
.450" Raised
|
| Combustion Chamber Size |
90cc
|
| Valve Cover Bolt Pattern |
Standard
|
| Valve Angle |
18°/4° Int, 11°/4° Exh
|
| Valve Spring Pocket Diameter |
1.750" O.D
|
| Max Valve Spring Pocket Machining |
1.750" O.D
|
| Warning: Do not machine spring pad any deeper | |
| Deck Thickness |
.750"
|
| Minimum Bore Diameter |
4.600"
|
| Flat Mill |
.005" per cc
|
| Angle Mill |
.0066" per cc
|
| Note:Angle mills might require a .120" Thick intake gasket. | |
| Minimum Cross Sectional Area |
3.699 sq. in.
|
| Spark Plug Dimensions |
14mm x .750" w/ Tapered Seat
|
|
CARB Status:This product is not legal for sale or use on emission-controlled vehicles and intended for dedicated race vehicles only. |
|
| Recommended Components: | |
| Intake Port Gasket | |
| Important: Do not use your AFR gasket as a template to port match your intake manifold as one AFR gasket is used for many AFR runner volumes. | |
| Exhaust Port Gasket | |
| Head Gasket, Fel Pro #1057 |
Fel Pro #1057
|
| Head Gasket, Cometic C5434 |
Cometic C5434
|
| Head Studs, ARP 135-4305 | |
| 1.8 Shaft Mount Rocker Arms T&D |
#3160
|
| 1.8 Shaft Mount Rocker Arms Crower |
|
| 1.8 Shaft Mount Rocker Arms Jesel |
#KPS-441172
|
| Suggested Manifold | |
| Suggested Manifold | |
| Spark Plug Starting Range |
Autolite 3932
|
| Distributor Standard Deck |
MSD #84697 or #8489
|
| Distributor Tall Deck |
MSD #85561 or #8547
|
| Valve Cover | |
| Valve Cover Gasket | |
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Part# 3708