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Disclaimer:        Take these air flow readings with a grain of salt. The readings may be 10% high.
                   The ratings may not be comparable to flow ratings from another flow bench.
                   Calibrations,set-up,etc. may be different than other flow benches also.
                   I think the main purpose would be the air flow comparison between the different heads.
                   Steve25 at PY suggested using a 1.37 correction factor to his numbers for 28" of water.
                   
    
                   Thanks-John


Ultimate Head Flow Charts


by Pete McCarthy and High Performance Pontiac


1958 No. 528511 (1958 370-cid 270-hp 4-bbl)
Date cast: J277	Grade: 3 (3 cfm seat leakage)
Valve sizes: 1.88/1.60
Intake(S)Flow(cfm)Exhaust(S)Flow(cfm) Exh./Int
.10046.10034.74
.20088.20061.69
.300119.30087.73
.400141.40098.70
.500148.500101.68
.600152.600102.67

1961-62 NO. 538177 (1961-62 195 & 389-cid)
Date cast: E152	Grade: 3 (3 to 6 cfm seat leakage)
Valve sizes: 1.88/1.60
Intake(D)Flow(cfm)Exhaust(S)Flow(cfm)Exh./Int.
.10049 57.10039.74
.20095 95.20075.79
.300119 127.300104.84
.400125 130.400117.92
.500130 133.500125.95
.600 130 133.600130.99

1963 No. 543797 (1963 389-cid 10.25:1 CR)
Date cast: A143		Grade: 1
Valve sizes: 1.88/1.60
Intake(D)Flow(cfm)Exhaust(S)Flow(cfm) Exh./Int.
.10054 63.10039.67
.200103 105.20078.75
.300126 127.300104.82
.400130 129.400124.96
.500131 130.5001341.02
.600131 130.6001391.07

1963 No. 9771980 (1963 421 Super Duty)
Date cast: none	Grade: 2 (2 cfm valve guide leakage)
Valve sizes: 2.02/1.76 (tuliped)
Intake(MP)Flow (cfm)Exhaust(MP)Flow (cfm)Exh./Int.
.10061 63 58 62.10047 42 39 42.70
.200115 119 115 110.20077 75 72 74.65
.300147 147 151 149.300102 99 98 102.68
.400169 165 164 165.400120 121 120 122.73
.500178 173 174 178.500132 130 130 134.75
.600185 183 178 183.600138 137 139 139.76
.700188 183 180 184.700140 140 142 141.77

1963-64 No. 9770716 (1963 421 HO & 1964 421 HO/389 GTO)
Date cast: J304	Grade: 2 (3 cfm valve guide leakage)
Valve sizes: 1.92/1.66
Intake(S)Flow (cfm)Exhaust(S)Flow (cfm)Exh./Int.
.10065.10033.51
.200115.20064.56
.300143.30086.60
.400149.400102.68
.500153.500110.72
.600155.600113.73

1965 No. 77 (1965 389 GTO & 421 HO)
Date cast: L124	Grade: 2 (3 cfm seat leakage)
Valve sizes: 1.92/1.66
Intake(S)Flow (cfm)Exhaust(S)Flow(cfm)Exh./Int.
.10063.10035.56
.2001l1.20066.59
.300136.30085.63
.400142.40098.69
.500145.500106.73
.600149.600110.74

1966 No. 093 (1966 389 GTO & 421 HO)
Date cast: D136	Grade: 2 (worn guides)
Valve sizes: 1.92/1.66
IntakeFlow (cfm)Exhaust(S)Flow (cfm)Exh./Int.
.10059.10034.58
.200117.20067.57
.300139.30091.65
.400144.400100.69
.500147.500104.71
.600149.600108.72

1967 No. 670 (1967 400 & 428 large-valve--GTO, GP, FB 400)
Cast date: J156  Grade:1 
(Note: valve inclination angle decreased to 14° from 20°)
 Valve sizes: 2.11/1.77
Intake port volume (2 ports): 152.3 & 153 cc's
Intake(D)Flow (cfm)Exhaust(D)Flow (cfm)Exh./Int.
.10073 75.10039 43.55
.200130 129.20076 79.59
.300148 150.300100 104.68
.400155 156.400117 117.75
.500161 160.500122 124.77
.600163 161.600129 128.79

1968-69 No. 16 (1968-69 400 & 428 large-valve D-port)
Date cast: A228	Grade: 2 (1 cfm seat leakage)
Valve sizes: 2.11 /1.77
Intake port volume (2 ports): 154 & 154.7 cc's.
Intake(D)Flow (cfm)Exhaust(S)Flow (cfm)Exh./Int.
.10071 74.10046.63
.200126 122.20084.68
.300153 155.300106.69
.400158 158.400124.78
.500162 167.500132.80
.600165 167.600140.84

1969 NO. 48 (1969 400 "Ram Air III" D-port)
Date cast: K308                  Grade: 2 (worn guides)
Valve sizes: 2.11/1.77
Intake(D)Flow (cfm)Exhaust(S)Flow (cfm)Exh./Int.
.10067 75.10038.54
.200116 119.20077.66
.300148 152.300103.69
.400156 159.400119.76
.500160 161.500128.80
.600165 166.600131.79

1969 NO. 722 (1969 Ram Air IV 400, round exhaust ports)
Date cast: none                      Grade: 1
Valve sizes: 2.11/1.77 (tuliped)
Intake port volume (2 ports): 182.6 & 183.6 cc's
Intake(MP)Flow (cfm)Exhaust(S)Flow (cfm)Exh./Int.
.10063 71 62 70.100 38.57
.200120 130 126 120.20079.64
.300156 172 164 158.300109.67
.400180 184 187 178.400131.72
.500194 193 195 190.500145.75
.600195 195 195 194.600151.78
.700197 195 197 194.700157.80

1969-70 NO. 44 (1969-70 Ram Air V Tunnel Port, 4-port exhaust)
Date cast: none	Grade: 2 (1 cfm seat leakage)
Valve sizes: 2.19/1.77 (tuliped, 3/8-inch width)
Intake(S)Flow (cfm)Exhaust(S)Flow (cfm)Exh./Int.
.10075.10037.49
.200129.20074.57
.300164.300100.61
.400196.400124.63
.500216.500140.65
.600233.600151.65
.700245.700159.65
.800253.800163.64

1970 No. 12 (1970 Ram Air III 400, D-port)
Date cast: H019	Grade: 1
Valve sizes; 2.11 /1.77
Intake(D) Flow (cfm)Exhaust(S) Flow (cfm)Exh./Int.
.10073 71 .10032.44
.200122 126.20075.60
.300151 151.300102.68
.400162 158.400115.72
.500164 162.500126.77
.600167 165.600132.80

1970 No. 64 (1970 455 GTO & 455 GP)
Date cast: I099	Grade: 2 (worn guides)
Valve sizes: 2.11 /1.77
Intake(S) Flow (cfm)Exhaust(S) Flow (cfm)Exh./Int.
.10065.10038.58
.200111.20075.79
.300138.30098.71
.400148.400111.75
.500153.500120.78
.600156.600125.82

1970 No. 614 (1970 Ram Air IV & LS1 400, round exhaust port)
Date cast: none	Grade: 1
Valve sizes: 2.11/1.77 (tuliped)
Intake(D) Flow (cfm) Exhaust(D) Flow (cfm)Exh./Int.
.10071 76.10040 33.50
.200128 122.20085 76.64
.300172 169.300117 117.69
.400200 201.400139 128.67
.500201 203.500150 139.72
.600202 203.600157 147.75
.700202 203.700163 172.83

1971 No. 96 (1971 400-cid 8.2:1 CR;  96 cc D -port)
Date cast: G 030			Grade: 1
Valve sizes: 2.11/1.77
Intake(D) Flow (cfm)Exhaust(D) Flow (cfm)Exh./Int.
.10067 73.10033 38.51
.200115 122.20074 74.62
.300144 148.30099 96.67
.400160 160.400111 105.68
.500165 166.500118 112.69
.600169 170.600122 118.71

1971 No. 66 (1971 465 D-port low compression)
Date cast: D011	Grade: l
Valve sizes: 2.11/1.77
Intake port volume (2 ports): 145.2, 144.4 cc's
Exhaust port volume (1 port): 141.4
Intake(D) Flow (cfm)Exhaust(S) Flow (cfm)Exh./Int.
.10072 70.10041.58
.200117 116.20083.71
.300149 148.300106.71
.400183 166.400117.71
.500171 174.500127.74
.600178 178.600132.74
.700181 180.700136.75

1971 No. 197 (1971 455 HO, round exhaust port)
Date cast: none	Grade: 3 (5 cfm seat leakage)
Valve sizes: 2.11/1.77
Intake port volume (2 ports): 171.5 & 171 cc's
Intake(S) Flow (cfm)ExhaustFlow (cfm)Exh./Int.
.10071.10039.55
.200122.20074.61
.300151.30096.64
.400167.400116.69
.500175.500125.71
.600177.600129.73
.700180.700132.73

1972 No. 7M5 (1972 250-hp 455-cid, 8.2:1 CR, 114 cc D-port)
Date cast: none	Grade: 1
Value sizes: 2.11/1.77
Intake(D) Flow (cfm)Exhaust(S) Flow (cfm)Exh./Int.
.10075 64.10037.53
.200115 114.20073.64
.300146 140.30093.65
.400161 160.400104.65
.500169 168.500111.66
.600175 171.600115.66

1972 No. 7F6 (1972 455 HO, round exhaust port)
Date cast: I167	Grade: 1 (NOS)
Valve sizes: 2.11/1.77 (flat-bottom, or "nailhead")
Intake(D) Flow (cfm)Exhaust(D)Flow (cfm)Exh./Int.
.10071 72.10037 35.50
.200118 121.20078 75.64
.300152 157.30099 97.63
.400168 171.400114 107.65
.500172 172.500119 112.67
.600176 174.600120 115.67
.700181 177.700121 115.66

1973-74 No. 46 (1973 350 D-port)
Date cast: K132	Grade: 2 (worn guides)
Valve sizes: 1.96 (45° seat)/1.66
Intake port volume (2 ports): 152.4, 152.2
Intake(D) Flow (cfm)Exhaust(S) Flow (cfm)Exh./Int.
.10054 63.10041.70
.20099 108.20081.78
.300145 150.300105.71
.400170 172.400118.69
.500181 181.500125.69

1973-74 NO. 4X (1973-74 400 & 455-cid D-port)
Date cast: J242	Grade: 2 (worn guides)
Valve sizes: 2.11 /1.66
Intake(D) Flow (cfm)Exhaust(D)Flow (cfm)Exh./Int.
.10065 60.10032 35.54
.200108 110.20067 69.62
.300144 142.30089 87.62
.400163 160.400106 103.65
.500171 165.500111 113.67
.600172 175.600125 119.70

1973-74 NO. 4C (1973-74 350 & 400-cid Calif. A.I.R. D-port)
Date cast: K072	Grade: 1
Valve sizes: 2.11/1.66
Intake(S) Flow (cfm)Exhaust(D)Flow (cfm)Exh./Int.
.10064.10033 34.52
.200109.20067 67.61
.300144.30086 91.61
.400160.400100 101.63
.500169.500107 109.64
.600172.600110 112.65

1973-74 No. 16 (1973-74 455 SD 290-hp, round exhaust port)
Date cast: K282
Grade: 1 (NOS), factory-installed 3-angle exhaust seat insert
Valve sizes: 2.11/1.77 (tuliped, 45° intake seat)
Intake(MP)Flow (cfm)Exhaust(D)Flow (cfm)Exh./Int.
.10062 64 64 61.100 45 43.60
.200112 121 116 109.20082 81.71
.300151 158 156 154.300108 109.70
.400169 171 173 172.400121 120.70
.500182 182 182 184.500127 125.69
.600188 190 190 191.600129 126.67
.700193 194 195 196.700130 127.66

1973-74 No. 16 (1973-74 455 SD 290-hp, round exhaust port)
Date cast: G143
Grade:1 (NOS), factory-installed 2 angle exhaust seat insert
Valve sizes: 2.11/1.77 (tuliped, 45° intake seat)
Intake(D) Flow (cfm)Exhaust(D) Flow (cfm)Exh./Int.
.10052 63.10040 35.65
.200114 121.20080 79.68
.300154 160.300106 107.68
.400172 176.400117 122.69
.500184 189.500122 127.67
.600193 195.600124 129.65
.700198 202.700125 129.64

1975 No. 5C (1975 350/400/455-cid D-port)
Date cast: F184	Grade: 1
Valve sizes: 2.11/1.66
Intake(D) Flow(cfm)Exhaust(S)Flow (cfm)Exh./Int.
.10063 63.10042.67
.200115 115.20078.68
.300143 146.300103.71
.400161 160.400118.74
.500164 165.500127.77
.600170 169.600131.77

1975-79 No. 6X (1975-76 400/455 & 1977-79 400 D-port)
Date cast: 0185	Grade: 2 (worn guides)
Valve sizes: 2.11/1.66
Intake volume (1 port): 154.0 cc's
Intake(S)Flow (cfm)Exhaust(S)Flow (cfm)Exh./Int.
.10067.10051.76
.200112.20083.74
.300140.30096.67
.400158.400104.66
.500163.500110.67
.600167.600113.68