The Small Port, High Velocity Torque Monster! - Information below is referring to fully assembled heads.
The AFR Emissions Legal (versions from 1969-94 with heat riser, CARB EO #D-250-2), 180cc intake port small block Chevy cylinder heads are available in your choice of straight or L98 angle plug versions. These cylinder heads feature a 75cc or 65cc combustion chamber with a 64cc exhaust port and a 3/4" thick head deck (ideal for nitrous or blower applications.) Standard valves are lightweight 8mm 2.020 intake and 1.600 exhaust with AFR's hardened ductile iron interlocking valve seats. The exceptional flow characteristics, ideal operating range of idle to 5500 rpm (higher rpm ranges possible depending on combination of parts), 23? valve angle, and standard valve spacing make this the perfect street aluminum cylinder head for 327 cid to 350 cid engines from 1955-86. Also available for 1987 to present engines with center bolt valve covers and 2 center intake bolts at 72? angle, AFR Part #0919. No special parts are required. Vortec style cylinder heads available also, AFR Part #0912. Drilling for centerbolt valve covers available as an option.
The exhaust ports are raised .100" over a standard GM L-98 cylinder head.
Note:
Hydraulic roller cams typically experience valve float at 6000-6200 rpm because of their fast ramp rates. AFR suggests you upgrade your springs to AFR part #8019, 1.270 O.D. with higher spring pressures to reduce chances of valve float associated with rpm's 6200 or higher, but smaller cams with less than .500 lift can rev to 6500 rpm with the included springs.
| Basic Package Components | Part # |
| 100% CNC Ported Combustion Chambers 100% CNC Ported Exhaust Ports 100% CNC Ported Intake Ports Competition 5-angle Valve Job |
| Specifications, Features, and Optional Supporting Components |
| Head Material |
A356 Aluminum |
| Intake Port Volume | 180cc |
| Intake Port Dimension | 2.050" H x 1.250" W x 5/16? Radius |
|
Intake Port Location
|
Stock |
| Exhaust Port Volume | 64cc |
| Exhaust Port Dimension | 1.450" H x 1.550" W |
| Exhaust Port Location | .100" Raised |
| Combustion Chamber Size | 65cc or 75cc |
|
Valve Cover Bolt Pattern
|
Perimeter Bolt |
| Valve Angle | 23? |
| Valve Spring Pocket Diameter | 1.460" O.D |
| Max Valve Spring Pocket Machining |
1.750" O.D |
|
Deck Thickness
|
.750" |
| Minimum Bore Diameter | 4.000" |
| Flat Mill | .006" per cc 60cc Maximum |
| Angle Mill | .009" per cc 55cc Maximum |
|
Minimum Cross Sectional Area
|
1.810 sq. in. |
| Note:Angle mills might require a .120" Thick intake gasket. | |
| Spark Plug Dimensions | 14mm x .750" w/Gasket Seat |
|
Carb EO#
|
D-250-23 |
| Exhaust Port Gasket, Fel-Pro #1404 | AFR #6834 |
| Head Gasket, 350cid Fel-Pro #1003 | AFR #6800 |
| Head Gasket, 400cid Fel-Pro #1014 | AFR #6802 |
| SB Chevy Head Bolt Kit, ARP #134-3701 | AFR #6310 |
| SB Chevy Head Stud Kit, 12 Point Nuts, ARP #234-4301 | AFR #6305 |
| Head Bolt Washers, Manley | AFR #6320 |
| Stud Girdle GM L98 | AFR #6200 |
| Suggested Manifold | AFR DPR #4804 |
| Spark Plug Starting Range | Autolite 3924 |
