SU Adjuster Nut

[Ray7Smith]

I need to lean out my carbs on my MGA, they are running too rich presently. Do I turn the adjuting nut clock wise or anti clock wise if I want to lean the mixture? It would appear that the nuts should be turned clock wise to lean the mixture.

Ray

 

[jlaird]

clockwise on SUs. In effect you want to enable the choke venture tube (jet) to move up into the carb further so the needle is down in it further. So if the nut is closer to the carb it will allow the choke (jet) to go up further and the needle then seats deeper into the jet and further on the leaner (fatter) part of the jet which restricts the flow.

Clear as mud, right?

 

[DrEntropy]

Let's assume the carbs are on the engine? If so, looking down from the top, the adjuster would need to be turned ANTI-clockwise to thread the jet up into the body, leaning out the mix. Go gently here as one flat is significant, too. :thumbsup:

 

[Ray7Smith]

Thanks for the input.

Ray

 

[jlaird]

Well, guess I was looking at the nut from where you would screw it, or at least thinking about it that way. Sorry if I confused.

That is the second time we have had that question in the past week Doc.

 

[DrEntropy]

Yeah, but if it's spread all thru the forum more folk will have it when needed. A search will hit at least ONE of the related threads that way.

It's kinda funny and worth a mention that the Zed S Strombergs work the same way: from the top with the long Allen wrench tool, to lean 'em you "unscrew" (anti-clockwise) the adjuster. It does just the opposite of the SU's, ie it moves the needle downward instead of moving the jet body up.

...well ~I~ think it's worth mentioning, anyway...