I'm in a Facebook group for Ford N series tractors. Built from 1939 to like 1952 I think. America's most popular tractor. Lots of them still running.
They're 4 cylinder flat heads, 2300 RPM, low compression, 23 hp.
Some people put flathead V8's in them. No meth involved. It's mostly old guys with beards.
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This one has a Cadillac engine.
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Another guy had one with a 300 straight six and another one had a 2.3L 4 cyl out of a Ranger.
One guy had a 302 in his and said it was running over 100 mph. I don't know what they do to the trans to gear it up though.
Mine goes 9 mph.