Re: Various parts for sale
Posted by DavidPackard on 2021/8/1 23:35:15
Carter data indicates that the 531 was intended for the 22/23 series 356 engine, and the 42-47 Super, while the 643 was intended for the 22/23 series 327 engine . . . so you’re looking for the ‘correct’ carburetor.
The main circuit mixture appears to be slightly different between the 531S (richest), 643S (middle), and 531 SA (leanest). This mixture adjustment was done by which metering rod set was installed. The main jet size is identical among the three carburetors. I don’t consider the amount of diameter change in the various metering rods as being a big deal, in that all three are close to one another.
The flange part number of the 531S & SA is different from the 643S, and the nominal idle mixture screw adjustment is different suggesting the potential of a porting difference in the flange. When I look at the individual pieces that would be used in the flange there seems to be the same start switch, throttle shafts and plates. The aluminum alloy cast parts are identical. Carter did not list the part number of the casting that contained the venturi. The sizes of all three venturi are identical between the carburetors in this discussion.
I would consider the 643 and 531 similar enough to be a good starting point for any of the engines listed, but if available the 643 would be correct for a ’49 Super 8.
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