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RE: Need help with SU's

To: "'spridgets@autox.team.net'" <spridgets@Autox.Team.Net>
Subject: RE: Need help with SU's
From: "Hanna, Mark" <mhanna@service.ball.com>
Date: Tue, 7 Apr 1998 10:13:31 -0600
Reply-to: "Hanna, Mark" <mhanna@service.ball.com>
Sender: owner-spridgets@Autox.Team.Net

> -----Original Message-----
> From: Hanna, Mark 
> Sent: Tuesday, April 07, 1998 9:51 AM
> To:   'Shannon'
> Subject:      RE: Need help with SU's
> 
> Shannon,
> It sounds like the rear carb may not be closing its 
> butterfly valve all the way. (this is a circular disk 
> inside the carb body that rotates with the throttle
> shaft) Its possible it has slipped out of position and is not allowing
> the throttle to close all of the way.This
> may be why that even with the idle adj. screw backed out all the way
> and the throttle closed , it is
> still hissing louder than the front carb. Also you mention "extra
> springs all over the place" If my memory serves me it should only have
> three springs. Please do not use extra or stronger throttle
> return springs . You risk wearing out the throttle 
> shaft bushing surface . If you do this the carb will leak air and
> upset the fuel air mixture . This is a common problem on old worn out
> SU's.
> Good Luck,
>                  Mark Hanna
>                  AN5L/13731
> 
>       -----Original Message-----
>       From:   Shannon [SMTP:squeedle@khoral.com]
>       Sent:   Tuesday, April 07, 1998 8:57 AM
>       To:     spridgets@autox.team.net
>       Subject:        Need help with SU's
> 
>       Here are my symptoms:
> 
>       1) When I adjust the fuel mixture per Haynes manual's
> instruction, the
>       back one is always too rich (as evidenced by carboned-up spark
> plugs).
> 
>       2) both linkages (choke & throttle) do not return the way they
> should, in
>       spite of extra springs all over the place.
> 
>       3) Corollary to 2, when I synchronize the carbs, a) it's almost
> impossible
>       to get the back one not to have a louder hiss, b) invariably
> when I
>       retighten the throttle linkage, 2 things happen - the idle speed
> decreases
>       and the carbs become de-synched (yes, the back one is louder).
> Then when
>       I drive the thing, the idle speed goes back up to 2000RPM
> 
>       I'm afraid I've messed up the throttle linkage by pressing too
> hard on the
>       bolts - the back one is hard to reach and tighten.
> 
>       Basically I'm not sure what to do about it.  I futzed with it
> for 2 hours
>       last night, & it seemed to be ok when I raised the throttle up,
> but then
>       this morning it was back to idling at 2000RPM once I got on the
> road.
> 
>       I can tell where it sticks, too, although I don't know the name
> of the
>       part(s).  Between the back carb & the linkage bolt there is some
> sort of
>       spacer and the 2-tine fork-shaped piece of metal, which links to
> the
>       little linkage pin thingie, and which actually seems to open the
> throttle.
>       If you press on this piece of metal firmly, the idle speed goes
> back down,
>       but this is not where it naturally returns to.
> 
>       Unfortunately the throttle adjustment screw on the back carb is
> almost all
>       the way out.  So basically I'm not sure what to do now - rebuild
> the
>       carb(s), get new linkage(s) or what? 
> 
>       Addendum:  when looking at it last night, I noticed that the
> front carb
>       piston was stuck open.  When I took it apart, I noticed that
> someone (NOT
>       me) did not reinstall it correctly - the needle was just resting
> in the
>       bottom, with the spacer sitting on top of it!  This was not like
> this
>       before I took it to a certain mechanic.  Anyway, I put the
> needle back the
>       way it was supposed to be.  Could this have caused some of these
> problems? 
>       Would it still cause these problems? 
> 
>       Sorry this is so long, but I wanted to give a full description
> so you kind
>       folks could help me out better.  :)
> 
>       Thanks,
>       Shannon 
> 
> ======================================================================
> ========
>               If I had a dime for every dime I had. . .

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