> Anyway, what happens with my car is there is an ENORMOUS
> build up of of
> water droplets that form all over the intake manifold and
> carb bodies.
Let me guess, you live where the relative humidity is high.
There are two things that cause the carbs and intake manifold to get cold
under cruise conditions. One is the liquid fuel evaporating (heat of
vaporization, same as the Dust-Off we discussed earlier). The other is the
intake air expanding when it reaches the intake manifold vacuum. According
to the ideal gas law (aka Boyle's law although not really), when a gas
expands, it absorbs heat (becomes cold). This is the reverse effect to
compressed air getting hot.
Generally the water on the outside is harmless and can be ignored. But when
the circumstances are just right, the condensation inside the carb can
freeze and form carburetor icing. The pilots in the audience will know all
about that, as it's a dangerous problem for small aircraft.
The cold can also cause fuel and/or water to condense inside the intake
manifold, which can enter the cylinders (and cause stumbling) when you
suddenly open the throttle. Heralds I believe actually had a drain in the
intake manifold to prevent this.
The cure is to introduce some carburetor heat. Usually the original setup
with the intake manifold bolted to the exhaust manifold in two places is
enough to prevent problems. But if that doesn't work for you (or you've
installed tubular headers without the attachment point for the intake
manifold), you may need to route heated air to the intake. Something like
the thermostatic heat stove used on Stags (and most cars of the 70s) would
work well, IMO. Or you could have an operator control (as aircraft normally
do) so you can apply heat only when it's needed. The heated air reduces
maximum power ...
-- Randall
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