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Old July 4th 10, 03:19 AM posted to rec.aviation.homebuilt
Morgans[_2_]
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Default Bobcat ultralight


"scooter01922"

I am a little puzzled as to why it seems that anyone with a twin
cly engine feels the need for 2 carbs. I would think keeping 1 carb in
tune is easier than keeping 2 running optimally and synchronized as
well.


In the case of opposed two cycle two cylinders, the use of one carb would
necessitate long intakes where the mixture would tend to condense out on the
walls of the pipes. They both usually are drawing at the same time, so it
would have to be twice as big of a carb.

If this is a multi cylinder with separated crankcases so the charge goes
into the cases, they are not connected internally, so separate feeds would
be necessary or use separate carbs.

Another advantage of individual carbs is that you can tune each cylinder for
equal head and exhaust temperatures, to make it run as smooth as is
possible. You need to have two carbs for that, as one would have to be a
compromise for each of the cylinders.

It isn't all that difficult to sync carbs, anyway. A simple set of manifold
vacuum gages is all that is necessary, for minimal needs. I once tuned a 4
carb MG by sticking a tube down the throat of each carb and listening to the
volume of the sucking of each carb. Guess what. That is how the book for
that car told you to do it! g
--
Jim in NC