Coming in in the middle...
>> I'm guessing that my carbs and/or fuel line lose their contents in a slow
>> fashion. It's running off a Weber downdraft (DGV ?) --- any ideas on where I
>> should look and what I should look for?
>
> Next time this happens, remove the top of the Weber and take a look
> at the float bowl. If it is empty, then you have slow leak in the carb
> somewhere (probably the idle circuit).
>
All the fuel to the idle circuit is supplied through the slow run jet. On
the DGV (and all other weber downdrafts I can think of), the slow run jet
and it's related passages is mounted well about the fuel level. Indeed, it
has to be or the fuel would siphon off every time the car is stopped.
Assuming no cracks in the carb body, there is only one place for the fuel
to escape... through a leaking accelerator pump diaphram. The pump is
mounted even with the bottom of the float bowl.
> Also take a look down the throat of the carb (with the throttle plates wide
> open) and see if you can see any puddles of gas. I know that with the Midget
> Weber manifold gas tends to puddle right underneath the carb (inside the
> manifold) - but the MGB Weber manifold may be a different design.
>
Gas puddled under the carb is not a sign of an internal leak in the carb,
it is a sign of really poor manifold.
The 1500 manifold (and CD175 adaptors) have an uphill run to them. This
causes fuel to puddle under the carb while the engine is running. This
cute feature, which causes all sorts of running problems, is not the Weber's
fault. It is all in the manifolds. Uphill runners, poor (and porous) castings,
and woefully inadaquate water heating.
Randy
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