This Page Last Updated on: Saturday, September 23, 2006 11:14 PM


Stock Pontiac Head Specs

* During my searching for information, I found quite a few discrepancies in the sources I was viewing. In light of this, the 'Year' entry, as indicated by the chart below, may actually represent the year that the heads were cast, versus the year that they were actually installed on an automobile.

** Also note... the combustion chamber volumes shown in the chart are based on various sources. Never assume that the volume is at stock spec. Always have your chamber volume measured, especially if you will be pushing the limit of an acceptable compression ratio for your combo.
Head Casting Number Year Engine Rated Horsepower Valve Size (Intake / Exhaust) Chamber Volume (or Compression Ratio if Volume Unknown) Stud Mounts Flow Charts
01 1977 301 ALL 1.72 / 1.50 8.2:1 CR Screw  
1978 301 ALL 1.72 / 1.50 8.2:1 CR Screw
1979 301 ALL 1.72 / 1.50 8.2:1 CR Screw
1980 301 ALL 1.72 / 1.50   Screw
1981 301 ALL 1.72 / 1.50 Screw
02 1978 301 ALL 1.72 / 1.50 8.2:1 CR Screw
11 1970 350 255 hp 1.94 / 1.66 8.8:1 CR Pressed
1970 400 265 hp 1.94 / 1.66 80 cc Pressed
12 1970 400 Ram Air III 345 hp (Firebird) 2.11 / 1.77 72 cc Screw Flow
1970 400 Ram Air III 366 hp (GTO) 2.11 / 1.77 72 cc Pressed
12 (Manual Trans) 1970 400 Ram Air III 330 hp 2.11 / 1.77 72 cc Screw
1970 400 350 hp (GTO) 2.11 / 1.77 72 cc Pressed
13 1970 400 350 hp (Grand Prix) 2.11 / 1.77 72 cc Screw  
13 (Auto Trans) 1970 400 330HP 2.11 / 1.77 72 cc Screw
1970 400 350 hp (GTO) 2.11 / 1.77 72 cc Pressed
14 1968 400 265 hp 1.96 / 1.66 90 cc Pressed
15 1968 400 290, 340 hp (FullSize) 1.96 / 1.66 75 cc Pressed
1970 455 360 hp (FullSize) 1.96 / 1.66 87 cc Pressed
16 1968 400 350 hp (Grand Prix) 2.11 / 1.77 72-75 cc Screw Flow
1968 400 330 hp (Firebird) 2.11 / 1.77 72-75 cc Screw
1968 400 335, 350, 360 hp 2.11 / 1.77 72-75 cc Screw
1968 428 375 hp 2.11 / 1.77 72 cc Screw
1968 428 390 hp 2.11 / 1.77 72 cc Screw
1969 400 340 hp 2.11 / 1.77 72 cc Screw
1969 400 Ram Air III 330,335,350,366 hp 2.11 / 1.77 72 cc Screw
1969 428 390 hp 2.11 / 1.77 72 cc Screw
1970 400 330 hp (FullSize) 1.94 / 1.66 78 cc Pressed
1973 455 SD 290 hp 2.11 / 1.77 111 cc Screw
1974 455 SD 290 hp 2.11 / 1.77 111 cc Screw
16 (Small Valve) 1969 428 360 hp 1.91/1.66 10:1 CR Screw  
1970 400 290 hp 1.94 / 1.66 78 cc Pressed
17 1968 350 265 hp 1.96 / 1.66 72 cc Pressed
18 1968 350 HO 320 hp 1.96 / 1.66 64 cc Pressed
22 1965 326 285 hp 1.88 / 1.60 60 cc Pressed
31 1968 400 Ram Air I 335, 360 hp 2.11 / 1.77 72 cc Screw
37 1968 400 Ram Air I 335, 360 hp 2.11 / 1.77 72 cc Screw
44 (Tunnel Port) 1969 400 Ram Air V 375HP (RA V) 2.11 / 1.77 67 cc Screw Flow
45 1969 400 265 hp 1.91 / 1.66 94 cc Pressed  
46 1969 400 290 hp 1.91 / 1.66 68 cc Pressed Flow
1969 428 360 hp 1.91/1.66 10:1 CR Screw
1973 350 150, 175 hp 1.94 / 1.66 96 cc Pressed
1974 350 155, 170 hp 1.94 / 1.66 98 cc Screw
1974 350 200 hp (GTO) 2.11 / 1.66 89 cc Screw
47 1969 350 265 hp 1.91 / 1.66 72 cc Pressed  
48 1969 350 HO 325 hp 2.11 / 1.77 64 cc Pressed Flow
1969 400 Ram Air III 330,335,350,366 hp 2.11 / 1.77 72 cc Screw
51 1975 455 AIR 2.11 / 1.66 124 cc Screw  
61 1967 400 290 hp 2.11 / 1.77 72 cc Pressed
1967 400 325, 333 hp (FullSize) 2.11 / 1.77 72 cc Pressed
62 1965 326 250 hp 1.88 / 1.60 70 cc Pressed Flow
1968 400 350 hp (Grand Prix) 2.11 / 1.77 72-75 cc Screw
1968 400 330 hp (Firebird) 2.11 / 1.77 72-75 cc Screw
1968 400 335, 350, 360 hp 2.11 / 1.77 72-75 cc Screw
1969 400 340 hp 2.11 / 1.77 72 cc Screw
1969 400 Ram Air III 330,335,350,366 hp 2.11 / 1.77 72 cc Screw
1969 428 370 hp 2.11 / 1.77 72 cc Screw
1969 428 390 hp 2.11 / 1.77 72 cc Screw
64 1970 455 360, 370 hp (GTO, Grand Prix) 2.11 / 1.77 87 cc Screw Flow
66 1971 455 325 hp 2.11 / 1.77 114 cc Screw Flow
75 1965 389 256 hp 1.88 / 1.60 92 cc Pressed  
76 1965 389 290, 325, 333 hp 1.92 / 1.66 70 cc Pressed
1965 421 338 hp 1.92 / 1.66 68 cc Pressed
77 1965 389 335, 338, 360 hp 1.92 / 1.66 70 cc Pressed Flow
1965 421 356, 376 hp 1.92 / 1.66 68 cc Pressed
91 1966 389 256 hp 1.92 / 1.66 92 cc Pressed  
92 1966 389 290, 325, 333 hp 1.92 / 1.66 10.5:1 CR Screw
1966 421 338, 350 hp 1.92 / 1.66 70 cc Screw
093 1966 389 335, 360 hp 1.92 / 1.66 68 cc Screw Flow
1966 421 HO 356, 376 hp 1.92 / 1.66 68 cc Screw
94 1966 326 250 hp 1.88 / 1.60 68 cc Pressed  
1971 350 250 hp 1.94 / 1.66 96 cc Pressed
95 1966 326 285 hp 1.88 / 1.60 10.5:1 CR Pressed
96 (Round Port) 1968 400 Ram Air II 340 hp (Firebird), 366 hp (GTO) 2.11 / 1.77 71 cc Screw Flow
1971 400 300 hp 2.11 / 1.77 96 cc Screw
97 1967 400 (Ram Air) 325, 360 hp 2.11 / 1.77 72 cc Screw  
98 1971 455 280 hp 1.94 / 1.66 114 cc Pressed
99 1971 400 265 hp 1.94 / 1.66 98 cc Pressed
140 1967 326 250 hp 1.92 / 1.66 9.2:1 CR Pressed
141 1967 326 285 hp 1.92 / 1.66 10.5:1 CR Pressed
142 1967 400 255, 260, 265 hp 1.92 / 1.66 90 cc Pressed
143 1967 400 290 hp 1.92 / 1.66 75 cc Pressed
1967 400 325, 333 hp (FullSize) 1.92 / 1.66 75 cc Pressed
191 (Round Port) 1971 455 HO 335 hp 2.11 / 1.77 111 cc Screw
197 1968 400 290, 340 hp (FullSize) 1.96 / 1.66 75 cc Pressed Flow
215 1968 400 350 hp (Grand Prix) 2.11 / 1.77 72-75 cc Screw  
216 1968 400 330 hp (Firebird) 2.11 / 1.77 72-75 cc Screw
1968 428 375 hp 2.11 / 1.77 72 cc Screw
1968 428 390 hp 2.11 / 1.77 72 cc Screw
1967 400 350 hp 2.11 / 1.77 72 cc Pressed
614 (Round Port) 1970 400 Ram Air IV 370 hp 2.11 / 1.77 71 cc Screw Flow
670 1967 400 325, 335, 360 hp 2.11 / 1.77 72 cc Screw Flow
1967 400 (Ram Air) 325, 360 hp 2.11 / 1.77 72 cc Screw
1967 428 360, 376 hp 2.11 / 1.77 72 cc Screw
1964 421 320 hp 1.92 / 1.66 70 cc Pressed
834 1964 326 250 hp 1.88 / 1.60 70 cc Pressed  
845 1964 389 267, 283, 303, 306 hp 1.92 / 1.66 70 cc Pressed
1960 389 SD   1.92 / 1.66   Pinned
535461 1961 389 ALL 1.88 / 1.60 69 cc Pressed
538177 1961 421 ALL 1.88 / 1.60 69 cc Pressed Flow
1962 389 ALL 1.88 / 1.60 69 cc Pressed
1962 421 ALL 1.88 / 1.60 69 cc Pressed
1959 389 368-373 hp 1.88 / 1.60 69 cc Pressed
540306 1959 421 368-373 hp 1.88 / 1.60 69 cc Pressed  
1960 389 368-373 hp 1.88 / 1.60 69 cc Pressed
1960 421 368-373 hp 1.88 / 1.60 69 cc Pressed
1961 389 SD 368, 373 hp 1.92 / 1.66 69 cc Pinned
1961 421 SD 368, 373 hp 1.92 / 1.66 69 cc Pinned
1962 389 SD 368, 373 hp 1.92 / 1.66 69 cc Pinned
1962 421 SD 368, 373 hp 1.92 / 1.66 69 cc Pinned
1961 389 SD 385, 405 hp 2.02 / 1.76 67 cc Pinned
1961 421 SD 385, 405 hp 2.02 / 1.76 67 cc Pinned
1962 389 SD 385, 405 hp 2.02 / 1.76 67 cc Pinned
1962 421 SD 385, 405 hp 2.02 / 1.76 67 cc Pinned
1963 389 215, 230, 235 hp 1.88 / 1.60 92 cc Pressed
543796 1963 326 250 hp 1.88 / 1.60 72 cc Pressed
543797 1963 389 267, 283, 303, 313hp 1.88 / 1.60 72 cc Pressed Flow
1963 421 320 hp 1.88 / 1.60 72 cc Pressed
1961 389 SD 385, 405 hp 2.02 / 1.76 67 cc Pinned
544127 1961 421 SD 385, 405 hp 2.02 / 1.76 67 cc Pinned  
1962 389 SD 385, 405 hp 2.02 / 1.76 67 cc Pinned
1962 421 SD 385, 405 hp 2.02 / 1.76 67 cc Pinned
1963 421 SD 390, 405, 410 hp 2.02 / 1.76 64 cc Pressed
1963 326 260, 280 hp 1.88 / 1.60 10.25:1 CR Pressed
548232 1964 389 215, 230, 235 hp 1.88 / 1.60 92 cc Pressed
5437796 1963 421 HO 353, 370 hp 1.92 / 1.66 72 cc Pressed
9770716 1964 389 325, 330, 348 hp 1.96 / 1.66 72 cc Pressed Flow
1964 421 HO 350, 370 hp 1.96 / 1.66 72 cc Pressed
1963 421 SD 390, 405, 410 hp 2.02 / 1.76 64 cc Pressed
9771980 1964 326 250 hp 1.88 / 1.60 70 cc Pressed Flow
9773345 1964 389 267, 283, 303, 306 hp 1.92 / 1.66 70 cc Pressed  
1964 421 320 hp 1.92 / 1.66 70 cc Pressed
1964 326 280 hp 1.88 / 1.60 10:1 CR Pressed
1967 400 350 hp 2.11 / 1.77 72 cc Pressed
9787671 1967 428 360, 376 hp 2.11 / 1.77 72 cc Screw
1971 455 HO 335 hp 2.11 / 1.77 111 cc Screw
4C 1973 350 150, 175 hp 1.94 / 1.66 96 cc Pressed Flow
1973 400 170, 185 hp 1.94 / 1.66 98 cc Pressed
1973 400 200 hp 2.11 / 1.66 98 cc Pressed
1974 350 155, 170 hp 1.94 / 1.66 98 cc Screw
1974 400 175, 190 hp 1.94 / 1.66 89 cc Screw
1974 400 200HP 1.94 / 1.66 98 cc Screw
1974 400 225 hp (Auto Trans) 2.11 / 1.66 98 cc Screw
1974 455 215, 250 2.11 / 1.66 114 cc Screw
4X 1973 400 200 hp 2.11 / 1.66 98 cc Pressed Flow
1973 400 230 hp 2.11 / 1.66 98 cc Screw
1973 455 215, 250 hp 2.11 / 1.66 114 cc Screw
1974 400 200HP 1.94 / 1.66 98 cc Screw
1974 400 225 hp (Auto Trans) 2.11 / 1.66 98 cc Screw
1974 400 225 hp (Manual Trans) 2.11 / 1.66 98 cc Screw
1974 455 215, 250 2.11 / 1.66 114 cc Screw
5C 1975 350 ALL 2.11 / 1.66 101 cc Screw Flow
1975 400 ALL 2.11 / 1.66 98 cc Screw
6H 1975 455 HO Non-Air 2.11 / 1.66 124 cc Screw  
1976 455 HO Non-Air 2.11 / 1.66 124 cc Screw
6S 1975 400 ALL 2.11 / 1.66 98 cc Screw
1975 455 AIR 2.11 / 1.66 115 cc Screw
1976 350 ALL 2.11 / 1.66 94 cc Screw
1976 400 ALL 2.11 / 1.66 101 cc Screw
1976 455 AIR 2.11 / 1.66 115 cc Screw
1977 350 ALL 2.11 / 1.66 94 cc Screw
1978 350 ALL 2.11 / 1.66 7.6:1 CR Screw
6X 1975 455 Late 2.11 / 1.66 7.6:1 CR Screw Flow
6X-4 (Small Chamber) 1975 350 Late 2.11 / 1.66 101 cc Screw
1976 350 ALL 2.11 / 1.66 94 cc Screw
1977 350 ALL 2.11 / 1.66 94 cc Screw
1977 400 (W72) 200 hp 2.11 / 1.66 94 cc Screw
1978 350 ALL 2.11 / 1.66 7.6:1 CR Screw
1978 400 (W72) 220 hp 2.11 / 1.66 94 cc Screw
1979 400 (W72)   2.11 / 1.66 94 cc Screw
6X-8 (Large Chamber) 1975 400 Late 2.11 / 1.66 101 cc Screw
1976 400 ALL 2.11 / 1.66 101 cc Screw
1977 400 180 hp 2.11 / 1.66 101 cc Screw
1978 400 180 hp 2.11 / 1.66 101 cc Screw
1979 400 ALL 2.11 / 1.66 101 cc Screw
7F6 (Round Port) 1972 455 HO 300 hp 2.11 / 1.77 111 cc Pressed Flow
7H1 1972 350 175 hp 1.94 / 1.66 80 cc Pressed  
7J2 1972 400 200 hp 1.94 / 1.66 96 cc Pressed
7K3 1972 400 250 hp 2.11 / 1.77 96 cc Screw Flow
7L4 1972 455 200 hp 2.11 / 1.77 114 cc Pressed  
7L5 1972 455 200 hp 2.11 / 1.77 114 cc Pressed
7M4 1972 455 250 hp 2.11 / 1.77 114 cc Pressed
7M5 1972 455 250 hp 2.11 / 1.77 114 cc Pressed Flow
X (Round Port) 1973 455 SD 290 hp 2.11 / 1.77 111 cc Screw  
1974 455 SD 290 hp 2.11 / 1.77 111 cc Screw