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Re: to SU or not to SU

To: mgs@autox.team.net
Subject: Re: to SU or not to SU
From: "A. B. Bonds" <ab@vuse.vanderbilt.edu>
Date: 11 Sep 1995 15:40:01 -0500
In <9509111945.AA19159@everest.den.mmc.com>, Graham Knight wrote:

>I drove it up and back (nice windy canyon :)
>and parked her in the driveway - popped open the hood -er- bonnet
>just in time to see gasoline dripping out of both sides of the
>throttle shaft openings on one of my SU's.  :( 
>
>        Now i figure if gas can get out, air can get in, so this
>is completely unacceptable. :| 
>
>        From what i've read this condition pretty much makes
>an SU carb - how should i say it - rubbish. Is this a fairly
>good assesment of my poor carb's fate - or can they
>be rebuilt??
>
>        My local Imports parts place quotes me $475 for a Weber
>carb and a manifold. I'd like to keep it stock, but, well,
>whaddya all think of the Webers?? Is this price too high?? (US dollars)

(a) Leaky throttle shafts are a fact of life in SUs of a certain age,
and it makes them deucedly difficult to tune.  If correct mixture is
set when idling, they will tend to be way too rich when running.

(b)  You can get SUs rebushed and have new throttle shafts installed
for about $50 each.  I believe the service is provided by either Joe
Curto or Apple Hydraulics.  Complete rebuilds are much more expensive,
and one would be wiser to get new carbies if going that route, since
SUs are once again in production.  DO NOT attempt to ream and install
oversize shafts yourself.  This requires precision, with which most of
us are not blessed.

(c)  Downdraft Webers work fine on the B engine.  They are more
tractable than SUs, but do not necessarily give the same performance.

I would choose the rebush option.
                                        A. B. Bonds


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