Pontiac Head Identification Numbers
6X and 4X Head Information
  • 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:

    A # 4 is 91 cc's (Installed on both 350's and 400's)

    A # 8 is 98/101 cc's (400)

    A # 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 143 400 cu.in. 260/333 hp D-PORT 1.92 1.64 72 CC
1967 061 400 cu.in. 333 hp D-PORT 2.11 1.77 75/80 CC
1967 670 or 97/997(rare) 400/428 cu.in. RA & 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