Beating dead horses (was, once: quote without comment)

["John Hertzman" <johnhertzman@domain.elided>]

In AD8-922 Luca takes exception to George Graves' statement that "The 2-liter
'Twin Spark' 4 cylinder engine of the late eighties and early nineties DID
HAVE 4-valves/cylinder-", Luca writing that "mmmhhhhh the Alfa 75 Twin Spark
sounds like a 2 valves per cylinder to me. Just the spark plugs were doubled
in each single combustion chamber...."

Luca is of course correct, and George is also correct except for the
chronology (not "late eighties") and for the debatable lineage of the
sixteen-valve Twin Spark two liters of the 155 and the FWD Spider and GTV.
They were not introduced until the early nineties, and they are arguably as
much, but no more, "Alfa" than the cars they were in. Certainly many people do
consider them Alfas, and I don't want to argue with them.

George Graves and Richard Welty agreed that there were indeed
crankcase-scavenged one-valve-per-cylinder two-stroke engines, but there were
also at least two types of one-valve-per-cylinder four-strokes. I don't know
of any rotary valve engines which reached production, but there were several
makes of production sleeve-valve engines. One could also argue for or against
including those engines in which a single combustion chamber with two valves
served two pistons; most, but I think not all, of these were opposed-piston
engines in which you could argue whether the cylinder(s) is/are single or
plural. Don't remember whether the Ariel, or perhaps some other bike, shared
combustion chambers between adjacent parallel cylinders.

John H.
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