Bob.........
An excellent explanation, indeed, covering all the points that I, with
mis-guided professionalism and no humor whatsoever, had completely
overlooked. Can we call upon you, at some future date, for a detailed
explanation as to why banging on the floor near the fuel pump might make the
car run, or tapping on the instruments improves their perceived accuracy?
And I'll gladly worry less in 1999 if you can tell me where I might get this
"little more" of which you youngsters so glibly speak.......:-)
May 1999 bring an end to the problems of this millennium!
Lawrie
-----Original Message-----
From: Robert Allen <boballen@sky.net>
To: Lawrie Alexander <Lawrie@britcars.com>
Cc: mgs@autox.team.net <mgs@autox.team.net>
Date: Wednesday, December 30, 1998 9:20 PM
Subject: Cold weather starting -- The Drill
>Geez, Lawrie, your New Year's resolution should be to get a little more and
>worry a little less. Of course pumping the pedal does some good as anyone
>capable of properly deciphering an SU carburetor schematic could tell you.
>
>You will notice that pulling the choke cable rotates the outboard shaft
between
>the two SUs. The shaft has a lever arm that pulls down on the jet tube and
>results in a larger fuel pool to be exposed to the venutri. Also on the
shaft is
>a cam that rotates around to engage an adjustment screw on the throttle
shaft.
>This has the inconsequential effect of cracking open the throttle plate.
>
>Now (and please pay attention) pumping the throttle effectively provides a
>jack-hammer action of the adjusting screw of the throttle shaft against the
cam
>on the choke shaft. Following Newton's 4th law (hitting stuff with a hammer
>makes things fall off), this pounding action is transferred via the lever
arm to
>the jet tube and, naturally, knocks off any junks of varnish/ ice crystals
that
>may have formed.
>
>Furthermore, as these varnish/ice junks fall into the pooled fuel in the
jet
>tube, the resulting splash releases a fuel-rich vapor. The pumping of the
>throttle causes the throttle plates to act as small fans wafting the splash
>residue vapor into the intake manifold.
>
>Quite elegant, I might add, compared to the mechanical complexity of an
>accelerator pump.
>
>Glad to be of service,
>--
>Bob Allen, Kansas City
>
>Lawrie Alexander wrote:
>
>> One more "For Pete's Sake" and I'm done for 1998, I
promise.................
>>
>> WHY, oh why do so many of you keep referring to starting procedures that
>> either call for "giving the pedal a few pumps" or (in another post)
>> "DO NOT PUMP THE PEDAL"? It takes but a moment to look at the SU
carburetor
>> design, or the Zenith Stromberg design, and see that THERE IS NO
ACCELERATOR
>> PUMP on either of these carbs!
>>
>> Any "pumping of the pedal" is doing nothing but exercise your ankle and
>> shorten the life of the cable and associated pivot mechanisms!
>
>
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