Quite correct 'Old Fella' I agree both counts. Oil bath air filters have been around for both up & down draft carbies for some time. My Holden FC had an oil bath filter & it was fitted to the downdraft stromberg, untill I fitted tiwn carbies, extractors, stage 3 yellow terra head &lowered the old girl, the next stage was to get booked for having an unroadworthy car
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Enter planes & girls, am paying for that bad mix forever!
'18W' I would say yr correct there the updraught carby was designed & fitted below the top of an engine (auto & aviation) to contain the overhaul shape/size of the engine to fit inside a streamlined cowl/bonnet.
CW