It sounds as though you are trying all this with the air cleaner off? Due to
the way the intake system was designed, Z-S equipped engines will only work
properly with the air cleaner fitted.
Lawrie
British Sportscar Center
-----Original Message-----
From: Eugene Harrison <eugh@2xtreme.net>
To: mgs@autox.team.net <mgs@autox.team.net>
Date: Sunday, November 14, 1999 6:31 PM
Subject: Z-S Carb too rich?
>In preparation for the required California SMOG check, I have been
>troubleshooting the rough running of my new project, a '79 MGB. By
>Disconnecting, plugging or blocking off, I have eliminated the gulp
>valve, the EGR valve, and the brake servo as problems. The stock
>manifold has been installed with a new gasket. With all the above
>temporally removed from the system, I have achieved a low idle speed
>with an occasional stutter. When I try to increase the speed of the
>engine it will increase to about 2000 RPM and then bog down to about
>1500 Rs and sound horrible. No amount of needle adjustment helped.
>Believing the carb to be excessively rich, I replaced the water jacket
>choke housing gasket with a solid one to block it off. The problem
>remains. Now here is the curious part that I need the MG list's
>collective wisdom to ponder. If while opening the throttle I Hold the
>piston with my finger so that it only goes up part way, the engine will
>rev freely to 3000 or above !!! Please help, Does holding the piston
>keep the needle from withdrawing and thus leaning the mixture? or does
>holding the piston cause a choking action that enrichens the mixture? I
>am tending to believe that maybe the needle jet is worn out, or the
>piston spring is too soft. The spring would be easy to replace but can
>the needle jet be replaced? It looks like it would require a special
>tool. At any rate the needle jet does not appear to be available from
>MOSS or VB. I put it to the list
>Thanks
>Eugene
>
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