Chris,
The SUs are HS4s if the fuel runs from the base of the float bowl to the
body via a flexible tube, and if the venturi diameter is 1-1/2". The
differences between the various HS4 models (designated by the AUD number)
are the metering needles, whether the rear carburetor has a vacuum take-off
for the distributor advance, whether the bodies have an inlet port for the
vent tube from the front engine side cover, whether the throttle plate has a
poppet valve or not, and the number and placement of the inlet/outlet pipes
on the float bowl lids.
None of these differences really matter unless you are trying to keep an
engine completely in its stock configuration, as all you have to do in a
custom set-up is make sure fuel reaches both carbs, can overflow if the
float sticks, that the needles suit the application, and that there are no
vents left un-plugged. Given a choice, vacuum for the distributor is
preferable from the rear carb rather than the manifold but even that can be
fixed if you carbs are the later style.
Do yours need rebuilding? Check the shafts for "wiggle" in their holes
(there should be none), make sure the pistons go up and down freely, make
sure the rubber pieces and gaskets look fresh, make sure the hole in the top
of the jets looks round and not oval and that the jet tube is still
flexible. Make sure both needles have the same number on them and that the
damper springs are identical. If all that passes muster, then give them a
try.
Lawrie
British Sportscar Center
-----Original Message-----
From: Chris Thompson <ct@cthompson.com>
To: mgs@autox.team.net <mgs@autox.team.net>
Date: Monday, December 11, 2000 9:10 AM
Subject: SU Info (And a kick in the butt)
(SNIP)
>Now, if some Guru out there could point me at a good SU reference, I'd much
>appreciate it.
>
>What do I look for on what needs to be rebuilt, if at all? If it's just
>minor refurb I'll take the attempt myself, if more than that, it'll get
>boxed up and shipped off to Lawrie. (It occurred to me that what I've paid
+
>Lawrie's rebuild is probably still cheaper than new from Moss :)
>
>Also, When I asked about 67 spec a few months back I was told (By kelvin
>among others) that the HS4 was what I wanted and someone mentioned specific
>AUD numbers. I seem to recall this being related to being appropriate for
>the type of dizzy I needed.
>
>How do I identify these carbs as being...
>A) Definitely HS4
>B) a specific AUD of HS4. There's many AUD numbers on different parts of
>this thing. Do I even need to worry?
>
>Thanks,
>
>-Chris
>
>P.S. the guy sitting next to me at dinner said "Oh you have an MGB? I had a
>65 MGB in college. God I wish I had that car back...." whereupon his eyes
>glazed and a bemused smile crossed his face. I told him that B's were
>plentiful and cheap around here. I may have caused another hapless soul to
>fall into the LBC pit again. Of course, his wife gave me a dirty look, but
>hey...
>
>________________________________________________________________________
>| Chris Thompson ct@cthompson.com |
>| 1973 MGB http://cthompson.com/mg/ |
>+----------------------------------------------------------------------+
|