Piston wont move up and down in SU

[MatsXJ]

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.

[MikeW]

Did you add oil to the dampers?

[Carl Beck]

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.

[Bruce Palmer]

No throttle response sounds like linkage didin't get engaged between the carbs.

Let us know what you find....

[beandip]

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

[MatsXJ]

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?

[Weasel73240Z]

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.