Chris.....
That the car should run only with the choke pulled all the way out, yet
three of the plugs showed very sooty, suggests lots of problems, I'm afraid!
so, I'll just answer the last two questions..........
There should be no perceptible play at the throttle shaft/body junction. New
shafts and bushings in the body sound like the cure, although you might be
lucky enough to find the bulk of the wear in your shafts so you could fit
oversize shafts after running a suitably sized drill bit or reamer through
the bodies. Replacing bushings requires some specialized equipment, best
left to an expert.
How to test the vacuum unit? Remove the distributor cap, suck hard on the
pipe to the unit (preferably with a hand-vacuum pump; gas fumes taste nasty
and are not good for you) and watch to see if the distributor plate rotates
a few degrees. If it does, and does not creep back while you maintain a
steady vacuum, the unit is OK.
Lawrie
British Sportscar Center
(Supplier of Moss rebuilt carbs and body re-busher extraordinaire)
-----Original Message-----
From: Chris Chandler <spawn@net-link.net>
To: MG List <mgs@autox.team.net>
Date: Monday, December 21, 1998 4:30 AM
Subject: SU Carbs
>I'm back again in need of counseling! <BG>
>
>I was out driving last night after adjusting the rocker/pushrod
>clearances, and all was well for a bit. Afeter the car warmed up
>however, it ran very poorly. It wouldn't run well unless the choke was
>all the way out, which would seem to me to indicate a very lean mix.
>
>So when I got home I let her cool off some and pulled the plugs. The
>first three were black as could be and #4 looked brownm like it should.
>I always thought that a black plug indicated a rich condition.
>
>The upshot is now I'm very confused! (Like I wasn't before, eh?)
>
>I went ahead anyway and removed the carbs for a closer look. As I was
>examining them, I noticed that the throttle shaft (is that the correct
>term???) has about 1/16" to 1/8" inch of side to side play in it. Is
>this normal (which I doubt), or is it worn (which I could easily
>believe)?
>
>If the shaft or bushing is worn, is it possible to replace one or the
>other? How difficult is it?
>
>Secondly, how does one check the vacuum advance to make sure it is
>working properly?
>
>Thanks again for all the help this far!
>--
>Chris
>'72 B Roadster (Too many pieces to count)
>'70 B Roadster "The Ghost"
>
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