Posted April 27, 200816 yr comment_245443 Hi guys, i have just removed my twin su's from the L24. I then installed the SU's in the exact reverse procedure of taking them off (i think). The pistons in the SU's dont move up and down now. I can lift them with my finger quite easily, but they just fall back down. When i start the engine, it just revs higher and higher and there is no throttle response. Does anyone have any ideas how to fix? Im thinking it is something simple but cant seem to find it. Thanks for your help. Link to comment https://www.classiczcars.com/forums/topic/27884-piston-wont-move-up-and-down-in-su/ Share on other sites More sharing options...
April 27, 200816 yr comment_245444 Did you add oil to the dampers? Link to comment https://www.classiczcars.com/forums/topic/27884-piston-wont-move-up-and-down-in-su/#findComment-245444 Share on other sites More sharing options...
April 27, 200816 yr comment_245450 Did you actually take the entire assembly off the intake manifold? Or did you disassemble the carb, with the carb body still attached to the intake?Are you sure you have the float level set correctly?Your problem would seem to be related to your linkage, or choke cables.... If you can lift the vacuum pistons and they fall back into place - they should be fine.FWIW,Carl B. Link to comment https://www.classiczcars.com/forums/topic/27884-piston-wont-move-up-and-down-in-su/#findComment-245450 Share on other sites More sharing options...
April 27, 200816 yr comment_245454 No throttle response sounds like linkage didin't get engaged between the carbs.Let us know what you find.... Link to comment https://www.classiczcars.com/forums/topic/27884-piston-wont-move-up-and-down-in-su/#findComment-245454 Share on other sites More sharing options...
April 27, 200816 yr comment_245474 First off , if you are expecting the piston that you can see while looking in the throat of the Carb, to move with the movement of the throttle linkage . You are mistaken. they are drawn up and down by the vacuum created by the suction of the engine drawing in air. As Bruce said it sounds like a linkage problem. Did you disassemble the carbs? If you removed the butterfly disks and didn't align them properly . This would have a major effect on the throttle response. Gary Link to comment https://www.classiczcars.com/forums/topic/27884-piston-wont-move-up-and-down-in-su/#findComment-245474 Share on other sites More sharing options...
April 27, 200816 yr Author comment_245480 Thanks for the comments, I forgot to say that i was aiming to adjust the fuel/air nut, in doing this i needed to adjust the little stopper that prevented me from turning the nut downwards. Problem is fixed now, looks like the stopper was sitting way too low. I still have problems with the tune, keep getting fuel firing out of the carbs at anything over 2000rpm, anyone know how to fix? Link to comment https://www.classiczcars.com/forums/topic/27884-piston-wont-move-up-and-down-in-su/#findComment-245480 Share on other sites More sharing options...
April 28, 200816 yr comment_245562 If you want to learn to tune your SU's, get the "Just SU's" video from ZTherapy. It'll be well worth the $20. They even have it on DVD now. Link to comment https://www.classiczcars.com/forums/topic/27884-piston-wont-move-up-and-down-in-su/#findComment-245562 Share on other sites More sharing options...
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