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Re: Carb Question

To: mgs@Autox.Team.Net
Subject: Re: Carb Question
From: "A. B. Bonds" <ab@vuse.vanderbilt.edu>
Date: 22 Oct 1997 08:42:38 -0500
In <Pine.OSF.3.96.971021175115.24149A-100000@fly.HiWAAY.net>, Blake Wylie wrote:
>
>I am having problems with my SU carbs, and someone has a Zenith-Stromburg
>in excellent condition that they will let me have if I want it (they put a
>Weber on theirs).  I don't have the money to replace them with a Weber
>(however, I may do so in later years).  Is this a good idea?

No.  Bad idea.

>The person
>also gave me an old dirty set of SUs for replacement parts.  Should I just
>start replacing some of the parts and try to tune the current ones up? Can
>anyone give me any help in tuning the SUs?
>Advice...comments...options...etc....   ????  
>
The replacement parts are probably just as bad as the original ones.
Most of the things that need to be replaced in an SU can be had new
for about $20 per carb.

Get the Haynes SU carbureter manual.  JC Whitney sells it for $11 or
so (as opposed to our friends at The Usual Vendors.)  This goes over
a step by step rebuild, with liberal photographs.  If the carbs aren't
severely worn, a rebuild is a fairly simple proposition.  The only 
tricky part is making sure that the needle is concentric with the
jet.  The SU carb toolkit (Moss sells it for less than $20) has a
little gizmo that makes easy work of this problem.

If the throttle shafts are worn on your carbs, the carbs must be
rebushed and the shafts replaced.  This is a precision operation that
shouldn't be done in your basement.  Apple Hydraulics will do this for
$50 per carb, which is reasonable.  Shaft wear is detectable by either
(1) wiggling on the shafts and feeling sideways slop, or (2) spraying
carb cleaner or starting fluid on the side of the carbureter (where
the shafts go into the body) while the engine is idling and hearing a
change in the engine speed.  If your shafts are shot, there is no way
you can ever get the carbs to behave correctly without repair.

                Good luck!      A. B. Bonds

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