['ol Pinion head]

There were slight differences in the 197's & 7F6's, the most obvious being the relocation of a water sending unit hole in side of the '72 head & the revised heat crossover passage. Chambers are the same, valves are the same, slightly more restrictive exhaust port on the '72 model 7F6's. Not all 7F6's had the notches in the intake side divider.

The 71 HO carbs were flowed at 832 cfm by a carb builder/racer in Alabama about 20 years ago. The '72 HO carbs were all 750 cfm. the difference didn't seem to mean much performance wise, as most have reworked both carbs for optimum performance with their combinations. For an engine combination that in bone stock condition was over by 5200 rpm , the larger cfm '71 HO carb reasoning has always bewildered me. Back to 750 cfm for '72 had to do somehow with emissions. In a race built RAIV, can see the need for larger carb...higher rpm range & higher volumetric efficiency will create a need for a bigger carb.