larger updraft carbs?

[JonE]

What has been interesting is seeing how eminently understandable all the Solex late 1920s/early 30s catalogues are for assessing the correct carb choice, jet choice and so on. This section shows the differences gravity makes for moving from updraft to sidedraft (on 30MOVertical and MOHorizontal) using the left hand column determinant of car's engine size in litres x max rpm - so say a mild Austin 7... c.3750 as 0.747x5000 yielding 19mm optimum choke size as horizontal, but 21 when updraft - with consequently larger jet. So presumably the later downdraft sees a further efficiency here. 
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