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

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

1963 No. 543797 (1963 389-cid 10.25:1 CR)
Date cast: A143		Grade: 1
Valve sizes: 1.88/1.60

1963 No. 9771980 (1963 421 Super Duty)
Date cast: none	Grade: 2 (2 cfm valve guide leakage)
Valve sizes: 2.02/1.76 (tuliped)

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

1965 No. 77 (1965 389 GTO & 421 HO)
Date cast: L124	Grade: 2 (3 cfm seat leakage)
Valve sizes: 1.92/1.66

1966 No. 093 (1966 389 GTO & 421 HO)
Date cast: D136	Grade: 2 (worn guides)
Valve sizes: 1.92/1.66

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

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.

1969 NO. 48 (1969 400 "Ram Air III" D-port)
Date cast: K308                  Grade: 2 (worn guides)
Valve sizes: 2.11/1.77

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

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)

1970 No. 12 (1970 Ram Air III 400, D-port)
Date cast: H019	Grade: 1
Valve sizes; 2.11 /1.77

1970 No. 64 (1970 455 GTO & 455 GP)
Date cast: I099	Grade: 2 (worn guides)
Valve sizes: 2.11 /1.77

1970 No. 614 (1970 Ram Air IV & LS1 400, round exhaust port)
Date cast: none	Grade: 1
Valve sizes: 2.11/1.77 (tuliped)

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

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

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

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

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")

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

1973-74 NO. 4X (1973-74 400 & 455-cid D-port)
Date cast: J242	Grade: 2 (worn guides)
Valve sizes: 2.11 /1.66

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

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)

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)

1975 No. 5C (1975 350/400/455-cid D-port)
Date cast: F184	Grade: 1
Valve sizes: 2.11/1.77

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

Pontiac Head Identification Numbers 6X and 4X Head Info: Stamping location to determine the cc's of the later 4X or 6X heads are as follows: Looking at the head from the exhaust port side, there are two drilled bosses for an A/C bracket on the passenger side (over the end exhaust port) on 4X or 6X heads. Look at the other end where there is a lone undrilled raised machined boss. This is where there will be a stamped number. The codes are listed below. The 6X head was installed on the 350, 400 and 455 Engines during the mid to late 70's The Boss Stamping to determine the cc's of the 6X heads are as follows: 4 is 91 cc's (Installed on both 350's and 400's) 8 is 98/101 cc's (400) 11 is 114 cc's (455) As far as I have seen all these heads came with 2.11/1.66 valves The 4X head was installed on the 400 and 455 during the mid 1970's. Most I have found are 455 stampings. The Boss Stamping to determine the cc's of the 4X heads are as follows: 1H is 114 cc's (455 Engines) ** Some have screw-in studs while others are pressed in. 3H 2.11/1.66 valves 98/101cc's. 4H 1.96/1.66 valves 98/101cc's 7H 2.11/1.66 valves 98/101 cc's These cc figures are approximates, as I have found most slightly higher. Intake Changeovers All V-8 Intake manifolds are interchangeable from 1967 thru 1971 and 1972 thru 1979. The difference is in the heat crossover size (taller after 1972) and an exhaust leak will occur unless the proper modifications aren't performed. ***Exempt; The 1969/70 RA V Pontiac and late 70's 301 Engine have a totally different intake configuration. YEAR CASTING # ENGINE SIZE EXHAUST STYLE INTAKE VALVE EXHAUST VALVE CHAMBER VOLUME 1958 528511 370 cu.in./270hp D-PORT 1.88 1.60 62 CC 1960 536109 389 cu.in. 215/348 hp D-PORT 1.88 1.60 72 CC 1960 535461 389/421 cu.in. 348/363 hp D-PORT 1.92 1.60 68 CC 1961-62 177 389 cu.in. 215/348hp D-PORT 1.88 1.60 62 CC 1961-62 540306 or 544127 389/421 cu.in. 368/373hp D-PORT 1.92 1.60 68 CC 1963 232 or 652 326 cu.in. D-PORT 1.88 1.60 55 CC 1963-64 796 or 797 195 4 cyl. 389/421 cu.in. D-PORT 1.88 1.60 62 CC 1963 980 421 cu.in. Super Duty D-PORT 2.02 1.60 66 CC 1963 345 389/421 cu.in. D-PORT 1.88 1.60 68 CC 1964 345 or 394 326 cu.in. D-PORT 1.88 1.66 71 CC 1963-64 716 389/421cu.in.HO 389 GTO D-PORT 1.92 1.66 68 CC 1965 22 or 62 326 cu.in. D-PORT 1.92 1.96 62 CC 1965 75 389 cu.in. D-PORT 1.92 1.66 68 or 92 CC 1965 76 421 cu.in. D-PORT 1.92 1.66 68/70 CC 1965 77 389 & 421 cu.in. HO D-PORT 1.92 1.66 68 CC 1966 094 or 095 326 cu.in. D-PORT 1.92 1.66 62 CC 1966 091 or 092 389 cu.in. D-PORT 1.92 1.66 70 CC 1966 093 389/421 cu.in. HO D-PORT 1.92 1.66 68 CC 1967 140 326 2bbl D-PORT 1.92 1.64 62 CC 1967 141 326 4bbl D-PORT 1.92 1.64 52 CC 1967 142 or 143/ or 061 400 cu.in. 260/333 hp D-PORT 1.92 1.64 72 CC 1967 670 or 97/997(rare) 400/428 cu.in. Ram Air & HO D-PORT 2.11 1.77 65/72 CC 1968 17 or 18 350/400 cu.in. 2 bbl Tempest/GTO/Firebird D-PORT 1.96 1.66 75 CC 1968 14 400 cu.in 265hp Big Car D-PORT 1.96 1.66 90 CC 1968 15 400 cu.in. 290/340hp Big Car D-PORT 1.96 1.66 92 CC 1968 31 400/428 cu.in. Ram Air D-PORT 2.11 1.77 72 CC 1968 1/2 R96A/R & A not on some end ports 400 Ram Air II Round Port 2.11 1.77 72 CC 1968-69 16 400/428 Ram Air & HO D-PORT 2.11 1.77 72 CC 1968-69 62 Big Car 400 cu.in. 350/375hp D-PORT 2.11 1.77 72 CC 1969 44 Ram Air V Tunnel Port TUNNEL PORT 2.19 1.77 67 CC 1969 47 350 cu.in. D-PORT 1.96 1.66 73 CC 1969 46 400/428 cu.in. D-PORT 1.96 1.66 72 CC 1969 45 400 cu.in. D-PORT 1.96 1.66 90 CC 1969 48 400/428 Ram Air & HO D-PORT 2.11 1.77 72 CC 1969 722 400 Ram Air IV Round Port 2.11 1.77 71 CC 1970 11 350 cu.in. D-PORT 1.96 1.66 73 CC 1970 12 400 Ram Air III D-PORT 2.11 1.77 72 CC 1970 13 400 D-PORT 2.11 1.77 72 CC 1970 15 455 cu.in. 360 hp D-PORT 2.11 1.77 87 CC 1970 64 455 HO D-PORT 2.11 1.77 87 CC 1970 614 400 Ram Air IV Round Port 2.11 1.77 71 CC 1971 94 350 cu.in. Big Car 250 hp D-PORT 1.96 1.66 80 CC 1971 99 400 cu.in. Big Car D-PORT 1.96 1.66 86 CC 1971 66 455 cu.in. 325hp D-PORT 2.11 1.77 101 CC 1971 98 455 cu.in. D-PORT 1.96 1.66 86 CC 1971 96 400 cu.in. D-PORT 2.11 1.77 96 CC 1971 197 455 cu.in. H.O. Round Port 2.11 1.77 111 CC 1972 7H1 350 cu.in. D-PORT 1.96 1.66 80 CC 1972 7J2 400 cu.in. D-PORT 1.96 1.77 (odd) 96 CC 1972 7K3 400 cu.in. D-PORT 2.11 1.77 96/98 CC 1972 7M5 455 cu.in. 250hp D-PORT 2.11 1.77 114 CC 1972 7F6 455 cu.in. H.O. Round Port 2.11 1.77 111 CC 1973 46 350 cu.in. D-PORT 1.96 1.66 89 CC 1973-74 4X 400 cu.in. D-PORT 3H/4H/7H on exh. boss 2.11 1.66 98 CC 1973-74 4X 455 cu.in. D-PORT 1H on exh. boss 2.11 1.66 114 CC 1973-74 4C 350/400 cu.in. D-PORT 2.11 1.66 87/114 CC 1973-74 16 455 cu.in. Super Duty Round Port 2.11 1.77 111 CC 1975 5C 350/400 cu.in. reported on 455's D-PORT 2.11 1.66 98/114 CC Late 1975-1976 6H 455 cu.in. D-PORT 2.11 1.66 121/124 CC 1975 51 455 cu.in. D-PORT 2.11 1.66 114/121 CC 1976 6S Calif. 455 cu.in. D-PORT 2.11 1.66 121 CC 1976 thru 1979 6X 350(4)/400(8)/455(11) cu.in. Digit located on exh boss D-PORT 2.11 1.66 92 thru 114 CC depending on cu.in. 1977 thru 1979 01 301 cu.in.Only Intake ports lay sideways D-PORT 1.72 1.5 68 CC Engine Building Tips 1 Engine Building Tips 2 675 BHP 350 Article KRE'S New Aluminum Heads: On the Dyno

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