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I don't know about the 3's, but I'm told that the early spit engines were Ferguson. That's what the points that I put in were.
[/ QUOTE ]As "Banjo" has already noted, it was the wet-liner TR engines that were derived from the Standard Vanguard AND Standard-Triumph-built Ferguson tractors. Spitfire motors are a whole 'nuther subject.
But Spitfires up to the mid-1970s used an AC Delco distributor rather than Lucas, and the wear bits (points, rotor, cap) in those Delco units fit a lot of American iron as well. I discovered around 1973 that the rotor was the same as that in my '51 Chevy, for example!