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RE: SU carb rebuild/tuning problem

To: "Datsun Roadster Mailing list" <datsun-roadsters@autox.team.net>
Subject: RE: SU carb rebuild/tuning problem
From: "Brian Hollands" <Brian_Hollands@adp.com>
Date: Sat, 17 Aug 2002 15:22:57 -0400
After Adam's thought I figured it best to mention the symptom.  If you have
excessive leakage at the throttle shafts you will have a high idle with no
way to lower it.  1200-1500 rpm.  Sometimes higher.  It's a vacuum leak and
behaves just like any other vacuum leak.  One of the results of this tends
to be that owners back the idle speed screws all the way off so that the
throttle plates contact the carb throat and will eventually wear a channel
into it resulting in an unusable carb body.  If the carb throat gets a
channel worn into it then it becomes difficult to properly meter mixture
around the butterfly at idle.

Brian '69 2000
Tampa, FL
http://web.tampabay.rr.com/oilleak/


-----Original Message-----
I mis-replied; I thought there was a problem before but you feared it might
still be there even though you hadn't installed them yet.  Please be aware
that there HAS to be some leakage there.  If it was perfectly sealed (no
air got through) the throttle shafts wouldn't turn at all.  What you're
experiencing may be normal or might not be.  If you're comfortable tuning
them, or have someone else to look at them, then I'm sure you're right, but
if you're not sure, then let someone else have a try to see if it's normal
before shipping them back.

///  datsun-roadsters@autox.team.net mailing list


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