[K Simmons]

I decided that while my car was down and my "Z fund" was empty I would clean-up the exterior of the SU carbs. I have read in several posts about reaching inside the front carb and raising the slide, disabling it, so you could set the lean/rich adjustment on the rear carb and vise-versa. While disassembling mine I noticed a little, spring loaded shaft on the carb body that, when pushed up, would raise the slide/piston about 0.5". I have never heard this shaft mentioned and was wondering if this is what it is for(nothing else makes sense).

BTW, these are the three-screw variety if that matters

And they look much better when they are cleaned up.

 

[luggnut73]

that will work but the finger in the throat is alot less difficult.

 

[joeytekno]

thats actually what that thing is there for.. probably so you can adjust it with the air cleaner on.. yeah like its easy to reach the adj. knob with the air cleaner in the way.. you should polish your carbs up its not hard.. get some sandpaper 400,600,1200,2000, and steel wool and a drill with polishing pad.. they come out nice.. then you can do the valve cover and thermostat housing and air cleaner and front cover and ... ****..

 

[Roadman]

Hi KSimmons----------Joey is right--those little spring-loaded pins are there for lifting the sliding piston. In the good old days of MGA's, Austin-Healeys and early Volvos, this was the best way to check for proper mixture. You lifted the pin, and the engine (when adjusted properly) would briefly run at higher rpm's and then drop to a ragged idle. If the idle didn't drop back, the setting was too rich. If the engine stalled, the mixture was too lean. I used this method on all my SU equipped cars back in the fifties and sixties. Worked pretty well, too.

Roadman

 

[Al 260Z]

Roadman! Do You Copy!

You got all kinds o neat tricks up your sleeve!
Great post above.
Does this also work on Z SUs? Don't see why not!

I think this is consistent with Norm's SU tune-up procedures posted under 'articles' at left.

Later!
----------- Al