Saturday, January 9, 2016

Art : Form Following Function

"32" designates the throat size, "DCO" designates side-draft, and "A3" designates a stock application.  Weber's side-draft
racing carbs were "DCOE's," up to a 48 millimeter throat size.  Downdraft Webers were common on racing engines as
large as the 7 liter American V-8's used in Can Am cars--also with two throats paired to a common float chamber.  And,
iconically, on Ferrari V-12's.  (Some Ferraris used 3 downdraft Webers with 4 throats sharing a common float chamber.)
Weber also made lots of "normal," cheap downdraft carbs, single throat or progressive secondary, found on
mass-produced Fiats.

When I was young, Weber carburetors hung on the sides of all respectable racing engines.  You could even get Webers on very high-end street cars, like Ferrari, Porsches with the Type 547 engine, and the Alfa Romeo Giulietta/Giulia Veloce.

They are beautiful because they look like they do exactly what they do do: feed a maximum amount of gas and air directly into the combustion chamber.  The "secret" of Webers was two throttle throats paired on a common float chamber.  Two Webers for a 4 cylinder engine, 3 for a 6, 6 for a 12.  This allowed the fuel mixture to be supplied directly to each cylinder, not through a manifold which potentially imbalanced it.

The float chamber and the float mechanism itself were designed to prevent fuel starvation in high-G turns.  Webers had complex internal fuel passages and jets, which optimized fuel/air mixture for engine speed and load.  I remember well the plastic jet tray of the dealership where I worked in the 1960's.  It was about 16 inches square, gridded into maybe 64 boxes.  It would have daunted any modern home health care nurse assisting a senior with the tray for his daily/weekly medication dosages.  The point was to get the fuel mixture exactly right for idle, mid-range low load, and high speed full load.  The ideal mixture was in turn dictated by application.  Street or race?  Mostly full-throttle or some medium speed part throttle?  Webers required precise set-up, but worked brilliantly when they were.  They still do in vintage racing.

And they're lovely to look at, compared to the black plastic, tangled pasta, manifolds that come on modern high performance cars (with electronic fuel injection).  Do Webers work as well?  No.  Did they work better than any other contemporary carb, or the early versions of mechanical fuel injection?  You bet!

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