[alfa] RE:Spica

["John Fielding" <johnf@xxxxxxxxxxxxxxx>]

Hi All,

Someone mentioned that Spica came up on Google as "Alpha Virginis".

FWIW Spica is a 14th magnitude star in the Virgo constellation.  The
constellation consists of several star clusters, some visible with the naked
eye and some that require a telescope to see properly.  The Virginis part of
the Virgo constellation has its main star Spica, by far the brighest star in
the Virgo constellation and because it is the brighest in the Virginis portion
is given the greek symbol Alpha denoting it as being the brighest in the
Virginis cluster, the next brightest would be Beta Virginis etc.

So what is the reason that a name of a star was chosen for the fuel injection
system?  Did the makers consider the Spica was a bright idea or a shining
example perhaps - tongue firmly in cheek.  There are many star names or
constellations used for automotive names, off the top of my head I can think
of Orion, Taurus, Gemini, Vega etc that have been used over the years.

Perhaps the intials S.P.I.C.A. stand for something like A.L.F.A. does?

BTW  I have never worked on a Spica system as they didn't come here, but I
have more than a passing acquaintance with the much maligned Lucas-CAV system
used on some British cars.  Many years back I owned a Triumph 2500 PI which
was a 6-cylinder engine of 2.5L fitted with the Lucas fuel injection system.
Never gave a minutes trouble despite the poor reputation the car suffered
from.  The same system and engine was used in several other Triumph versions,
the TR6 and Vitesse being two that come to mind.

The Lucas-CAV system is similar to the Bosch K-Jet system but it is a pulsed
high pressure injection with injector nozzles like a diesel injecting into the
inlet manifold ports.  The original design was used on the early Formula 1
cars, like the BRM, with slide throttles.   The production version used
individual butterfly throttle bodies.  The fuel distributor had a chambered
revolving portion similar to a 6-shooter.  The 6 chambers (for a 6-cylinder
engine of course) when rotated lined up with the 6 outlet ports and the amount
of fuel injected was controlled by pistons that ran in and out of the chambers
to alter the volume.  As long as the major settings were left alone they ran
reliably.  My late father in law worked at the Lucas factory in Liverpool
where the CAV design was manufactured and he was employed in the pump test
department.  Working with petrol/gasoline for something like 30 years
eventually took its toll and he died of a lung condition.  Anyway he taught me
all there is to know about the system and warned me not to mess with the
adjustments unless he was present to oversee the work!  The same system was
used on allied fighter aircraft towards the end of WW2.

The injection pressure was quite high, around 30 atmospheres as I recall.  The
main fuel pump was a bronze gear pump driven by a modified windscreen wiper
motor that lived in the boot and had a water seperator which had to be drained
weekly, and supplied fuel to the metering distributor at about 9 atmospheres.
The camshaft driven pump raised this to the final pressure and on the Triumph
engines the pump plugged into where the spark distributor lived on the block
side.  The spark dissy then plugged into the top of the Lucas portion, a neat
arrangement.  An inertial switch fitted on the firewall would trip on impact
and cut off the 12V to the pump, or in my case if I did an emergency stop!
That had me going for about a day until I figured out why the engine suddenly
stopped.

It was easy to tell if an injector was plugged.  The injectors where connected
with nylon hoses and by grabbing these in the hand you could feel the distinct
pulsing.  If the pulsing was weak or non existent on one hose it meant that
injector was fouled up and needed cleaning.  This simply meant undoing the
fuel union on the injector and unscrewing the injector from the manifold.
Normally the tips were just fouled with carbon and a rub with a fine brass
brush and washing in petrol cured the problem.

With the emissions legislation being tightened up the system fell out of
favour and the more modern Bosch L-Jetronic replaced it.

John
Durban
South Africa
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