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 Red SU jet adjustment issue

 Created by: MrBeetleman
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 Posted: Jul 1, 2018 04:19AM
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US
The jet tube should not rotate with the nut. As you turn the nut it ( the nut ) moves up or down the threaded portion and pushes the jet tube up or down but by design the tube can't spin. Did I read the question right? Steve (CTR)

 Posted: Jun 30, 2018 09:16AM
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Thanks for the tips. I'll check out that site, and first off check the motion of the choke. 

 Posted: Jun 30, 2018 09:00AM
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When you remove the piston/needle you will be looking onto the top of the jet.  After observing its position go to the passenger compartment and pull the choke cable out.  Return to the carb and look at the jet again to see if it has moved down.  If it has not moved down, the jet may be stuck from corrosion and fuel gum/varnish.  Obviously if the jet has not moved down you have to free it up.

Do not mess with the nut securing the jet bushing to the underneath side of the carb body unless you are rebuilding the carb.  The top nut holds the jet bushing in place, concentric with the needle.  If you loosen that top nut you will have to re-center the jet which presumably you don't need to do at this point.

Since the SU seems to be new to you, visit the Burlen.co.uk website.  Under the SU tab you will find tech articles explaining how the SU works.   You will also find articles on how to adjust HS series carbs.  

Doug L.
 Posted: Jun 30, 2018 08:35AM
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I've got a 1973 austin mini with a single SU carb. I'm trying to lean out the air/fuel mixture by turning the jet adjustment nut.? It turns, but wasn't seeming to change anything. I removed the piston, and noticed that when I turn that nut, the jet isn't rotating. Do I need to loosen the lock nut that is up closer to the body of the SU? The car has been sitting for quite a while, so is it possible that the jet is "stuck"?