~ 1800 trivia, there were three models: 1800S, 1800E, & 1800ES.
Four, actually: you're omitting the initial run designated as
P1800, which were built by Jensen in England and are therefore
the only ones we *ought* to be talking about on this list.:-)
I believe that the Jensen-built cars ceased in 1967 and that
the 1800S designation took over the following year.
~ I have both an 1800S and a '57 MGA, with the Vo getting most attention these
I recently had the exquisite pleasure of driving out in the
M.G. to rescue Kim's nearly immaculate 122S from a roadside
emergency (which ended up being ludicrously simple -- a loose
fuel fitting on the twin SU HS6s). In fact, the simplicity
of the fix is one reason Kim is so interested in getting
her hands on the M.G. motor. She realized that if she had
known what to look for, she could have saved herself a walk
the other day.
As a final Volvo/Britcars connection, note that the bolt
spacing of HS4 and HS6 carburettors is claimed to be identical
(though the sixes use four bolts and the fours use two; it's
the diagonal spacing that matters). This means that cars such
as M.G.s which came with dual HS4s can use HS6s from Volvos of
various years as part of a performance upgrade (though you'll
need to enlarge the manifold as well in order to flow enough
air to make the bigger carbs worth using). Note however that
some later HS6-equipped Volvos (the 140 series) have a truly
bizarre setup using secondary throttles; I've read about them
in the manual but I've never seen one in action.