>I have heard that the SUs are a better replacement for the 175CDs than
>the dual webers are. From someone who should know, too.
Depends on your application. The SUs make great street
carbs because the variable venturi (dashpot) on them
gives them high mixture velocity at low speeds. This
helps our fine old machinery fill their cylinders that
much better at low RPM.
I know several people who converted back from Webers to
SUs on Spridgets and MGBs because the SUs work so well
as street carbs. (There are other reasons on the A- and
B-series engines, mainly port configuration issues that
make two straight-shot carbs flow better than two barrels
of a Weber with curved intake runners to the ports, but
that's specific to these motors.)
Note also that SUs are owner-tweakable; that is, you can
twiddle, tweak and frob them till you get them running
pretty well. Webers require swapping jets, air correctors,
emulsion tubes and lots of other parts that you have to have
(or have access to) in order to get the most out of them.
Having owned a car with Webers that were set up correctly,
I'll say that I really like them. If they're set up right,
they're marvelous, but not many people have the patience
(spelled with judicious application of $$$) to get them
set up right.
So in closing:
- SUs are easy to twiddle till they're about right
- You don't need to buy extra parts for SUs to get
them pretty close to correct
- They provide good low-end response by virtue of
the dashpot mechanism
- Webers can be better if you are a Weber wizard,
but expect some time and expense to get them right
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