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Re: Carbs

To: mgs@autox.team.net
Subject: Re: Carbs
From: David Councill <dcouncil@imt.net>
Date: Tue, 03 Jul 2001 18:48:28 -0600
Bill,

I'll send this reply to the list too since it might prove helpful. I have a 
fair working knowledge of SU carbs although miniscule compared to some on 
the list. There are several things that could cause your carbs to run rich 
but since you mentioned tightening the mixture adjusting nuts all the way, 
I would suspect the jet tube placement as a place to look.

I patched together a quick set of pictures here:
http://www.imt.net/~dcouncil/mg/65carbs.html

My son's error would cause symptoms like yours. Or alternately, your choke 
linkage could be adjusted in such a way that the jets would be lowered, 
making any attempt to lean your mixture with the mixture adjustment nuts to 
be futile.

The default setting of "twelve flats" on the mixture adjusting nuts is 
usually a good setting. That is twelve sides of the nut or two complete 
rotations down after tightening the nut all the way. I've tried all those 
fancy ways of tuning and even used the Gunson colortune tester, but in the 
end I've always ended up with twelve flats summer and 14 flats during the 
winter.

David
67 BGT
72 B

At 11:56 AM 7/2/01 -0400, you wrote:
>David,
>Thanks so much for the reply. Any pictures with descriptions of the parts
>described would be VERY welcome. When I tighten the jet adjusting screw,
>am I not making the mixture leaner? (Meaning that raising the jet closer
>to the jet needle makes the mixture leaner.) That's what I have been
>assuming, but I do get a lot of black residue on the plugs indicating too
>rich a mixture(?). Obviously, my knowledge on this subject is VERY
>limited, but I am trying.
>Thanks again.
>Bill

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