DATA FOR STOCK PONTIAC CYLINDER HEAD VALVE FLOW @ 22" WATER.

ENGINE "A" = 1970 455HO (ANY 2.11" D-PORT)
ENGINE "B" = 1971 455HO (ALSO 69-70 RA-4)
ENGINE "C" = 1973 455SD

-VALVE LIFT-  -ENGINE-  -I/E-  -CFM-
  0.100"         A        I      65
    *            A        E      35
    *            B        I      70
    *            B        E      30
    *            C        I      50
    *            C        E      40
  0.200"         A        I     215
    *            A        E     140
    *            B        I     225
    *            B        E     125
    *            C        I     200
    *            C        E     155
  0.300"         A        I     390
    *            A        E     260
    *            B        I     440
    *            B        E     235
    *            C        I     385
    *            C        E     275
  0.400"         A        I     455
     *           A        E     335
     *           B        I     540
     *           B        E     320
     *           C        I     510
     *           C        E     355
  0.425"         A        I     470
     *           A        E     350
     *           B        I     570
     *           B        E     335
     *           C        I     545
     *           C        E     470
  0.450"         A        I     480
     *           A        E     365
     *           B        I     585
     *           B        E     350
     *           C        I     580
     *           C        E     380
  0.475"         A        I     430
     *           A        E     380
     *           B        I     535
     *           B        E     375
     *           C        I     600
     *           C        E     385
  0.500"         A        I     435
     *           A        E     390
     *           B        I     550
     *           B        E     390
     *           C        I     625
     *           C        E     390
  0.550"         A        I     455
     *           A        E     430
     *           B        I     580
     *           B        E     430
     *           C        I     655
     *           C        E     430
  0.600"         A        I     485
     *           A        E     455
     *           B        I     585
     *           B        E     470
     *           C        I     675
     *           C        E     415
  0.650"         A        I     550           
     *           A        E     515
     *           B        I     600
     *           B        E     525
     *           C        I     585
     *           C        E     425

NOTES:
  
  
 ENGINE "A": INTAKE FLOW DROPS 485 TO 435 (10.31%) AT 0.460" LIFT AND DOES
             NOT RECOVER UNTIL 0.5875" LIFT.
               
 ENGINE "B": INTAKE FLOW DROPS 590 TO 525 (11.02%) AT 0.460" LIFT AND DOES
             NOT RECOVER UNTIL 0.625" LIFT.