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Search By Pontiac Cylinder Head Codes



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Pontiac Cylinder Head Search Interface


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Engine:
Hp:
Code:
Valve:
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Chart to mill Pontiac Cylinder Heads
Chart of C.R. of Pontiac Engines and Heads
C.R. Percent Power Loss


Pontiac made closed chambered heads until 1967.In 1967 Pontiac made some open chamber heads(i.e. 061).After 1967 the heads were open chamber heads.

Exhaust Crossover Port Matchings
With HeadAnd ManifoldUse Gasket
1965-711965-711965-71
1965-711972-791972-79
1972-791972-791972-79
1972-791965-711965-71**

** Use sheet stainless steel block off plate.

In 1973 Pontiac started stamping extra numbers (1/4" tall) on their heads.These head numbers represented chamber sizes.They are usually stamped on the machined pads by the valve covers.



Head ID Location Picture


1973/74 Stampings on Head codes - 4X, 46, 4C, 16/X

Stamped ID Head # Code MVMA Chamber Vol. Valve Diameter Valve Length CID
1 / 1H 4X 112.30 cc's2.11/1.66 valve4.78" 455
2H 4696.17 cc's1.96/1.66 valve4.86"350
3 / 3H4X98.21 cc's2.11/1.66 valve4.86"400
4 / 4H4X98.94 cc's1.96/1.66 valve4.86"350/400
5H 4C (AIR)96.17 cc's1.96/1.66 valve4.86"350
6H 4696.17 cc's1.96/1.66 valve4.86"350
6H 16/X110.74 cc's2.11/1.77 valve4.97"455 SD
7 / 7H 4X98.21 cc's2.11/1.66 valve4.86"400
8 / 8H4C (AIR)98.94 cc's1.96/1.66 valve4.86"400
*All rocker arms are threaded beginning with Motor Unit Number 709986 assembled on or about May 7, 1973.


=======================================================================

5C heads were installed on engines until around mid 1975 then dropped

  • -5C-4- 1975 350 4bbl, 2.11/1.66" valves, 4.960/4.949" valve length, 30/45 degree seats, threaded studs, 93cc
  • -5C-7- 1975 350 4bbl AIR, 2.11/1.66" valves, 4.960/4.949" valve length, 30/45 degree seats, threaded studs, 93cc
  • -5C-8- 1975 400 4bbl, 2.11/1.66" valves, 4.960/4.949" valve length, 30/45 degree seats, threaded studs, 101cc
  • -5CX-8- 1975 400 4bbl, 2.11/1.66" valves, 4.960/4.949" valve length, 30/45 degree seats, threaded studs, 101cc
  • -5C-9- 1975 400 4bbl AIR, 2.11/1.66" valves, 4.960/4.949" valve lengths, 30/45 degree seats, threaded studs, 101cc 5I (51) heads for the 455:
  • -5I-6- 1975 455 4bbl 2.11/1.66" valves, 30/45 degree seats, threaded studs, 124cc ======================================================================= The 6X castings started being installed on engines after about 2/21/75 (cc's are factory reported, may actually be different)
  • 6X-4 350(and 77-79 T/A 6.6), 93cc, 2.11/1.66"
  • 6X-6 455, 114cc ? /124cc, 2.11/1.66"
  • 6X-8 400, 101cc, 2.11/1.66"
  • 6H-6 455, 124cc, 2.11/1.66"
  • 6S-7 350 w/AIR, 93cc, 2.11/1.66"
  • 6S-9 400 w/AIR, 101cc 2.11/1.66" The 6X-4 and 6X-8 were the only heads used after 1976. =======================================================================

  • Stampings on 46 Head Code

    Just some more codes and sub codes for the 46's.One set is from a "WP" 74 GTO,
    one set
    from a 74 "YS" GTO 350 and 1 from a "ZB".Very interesting.All small
    valve of course.
    
    
              WP HEADS               YS                  ZB
            
    screw in studs               same                  pressed
    "6H" sub code               "H6" subcode          no subcode
    K093-K133 date codes        K093-K103            I103-I213
    3.170"wide scallop        3.230" wide            same
    .970" deep scallop        1.060" deep            same
    
    Seems Pontiac followed tradition in the fact that auto's got a little
    less cr than stick.Contrary to belief,48/62/16/12/13 are all rated
    72cc.Not true.12 and 48 are 8-10cc less than the auto heads.
    

    (Let me know if you find any more information on these codes or any not listed.)


    Pontiac Intake Manifold Years Interchange

  • 1957-1958
  • 1959-1960
  • 1961-1964
  • 1965-1979
  • Does not apply to 301 or the RA V