Steve Plucker is indeed the guru Ford A numbering and that number does not fit any known sequence. As he says the English ones were "omitted ones" from the USA list. I think some of the English ones, which had a 2043cc engine, may have AF as a prefix.
The so-called English ones may actually have been cast in Cork Ireland, but we have old archive footage of cylinder boring being done on them in England. The 3285 cc and 2043cc engines look externally identical except that the small capacity engine has a "land" between each cylinder on the Left side of the block whereas the 3285 cc has the land only between cylinders 2 and 3. You can thus quickly identify which it is. The stroke was the same on both engines but the bore of the smaller engine was 3.055 inches and I think the internal bore of the exhaust manifold was slightly smaller- externally the manifold was same. Externally the cylinder head was the same but a smaller combustion chamber for the 2043cc .The venturi and jet sizes of the Zenith were different. Of course you need to be aware of the other LHD/RHD difference- lug on manifold to take mechanism for advance/retard rod, slightly different bushing on clutch/pedal shaft, as well as obvious things like cenrtral accelerator attached to steering column, bellhousing, steering box and associated steering components. Our UK vehicle registrar
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