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HS6 spindle's, springs and needles

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Evening all,

My HS6 dolly springconversion for the gt6 was supposed to be all finished, but I negated a few bits and unsure whether it's going to be ok.

The first is the throttle spindles have no individual return springs on them. I couldn't find a part diagram with them on. Will I be able to leave as is and get away with a couple of return springs mounted to a bracket on the manifold or somthing? Should be easy to make and weld somthing up.


Secondly, I'm not sure on the exact terms here so dont get to angry with me :biggrin:. Picture below: is this acceptable? The gap between the motion lever and the carb bracket seem a bit large? Is it normal?


Lastly, needles. Carbs have the std dolly sprint needles, I will double check tomorrow. I was hoping to talk to anyone with a similar setup and gauge what sorts of needles I might get away with just to get it run in. Running a standard gt6 mk2 engine. I'm going to have a headache setting them up as they've been rebuilt so mixture settings are way off. Is there a rule of thumb for how many turns from say from fully tight mixture nut to a rough position to get it started?

Thanks again,



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I would say you do want individual return springs on the carbs as otherwise it's really hard to set the linkages so you get a consistent return to idle without the carbs fighting each other (why you have that gap).  Most twin arrangements have 3 springs.  One for each carb spindle and one for the collective linkage.  The later SUs have an annular spring that sits around one end of the spindle and these are best for not causing wear to the spindles and bushes, but as I don't see those you will need to arrange something like this.


Pretty sure that I have read that the Sprint needles work ok on the 2L sixes but no personal experience.  There is also a T2000 (2000 TC?) that has HS6s so they may be worth looking up.  (I do have the book but not to hand - say if you get stuck and I'll look it out).  This technique worked ok for me when using HIF4s in the Vitesse years ago as there is also a version of the 2000 saloon with HS4s and the needles from that worked ok.

Basic setting is wind the jets up until they are exactly level with the bridge, then two full turns down.  That'll get you going and is usually not far off right.

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I have Sprint carbs on my Vitesse, two return springs, one per carb, fitted on a 2.5s manifold which has two lugs cast in it for return springs. Fitted them as they came, not checked the needle, short dashpot Sprint Hs6 SU's, no reason to believe they are not standard Sprint needles.

Plugs are the right colour, and the car goes very well. I do have a 631 equal length exhaust manifold which probably helps.

Uploaded a video recently on Vitesse engine rattle, engine and ancillary section, where you can see how they are set up.

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Hello Speedysix,

aim to set the tabs on the throttle spindle more or less central to the slot in the carburettor link. More important to set them such that as the throttle is opened  the two tabs pick up the links simultaneously, i.e. so both carburettors start to open together. This needs to be done after they are balanced.


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  • 2 weeks later...

Apologies for the delayed response chaps, been very busy this week. I see once again this forum is such a brilliant community and resource! Thanks very much guys. Ill be mocking something up with the return springs similar to what nick has shown and will be adjusting the mixture as described also to get her going when the engine comes back.

Mark thanks very much, I had a look at the video (glad the rattle is sorted now!), I have a good idea how to mock something up.

Alec and Martin thanks also, its very relieving to know i can get away with standard needles for now!

Ill add a picture of the setup once its mocked up, been trying to hunt some hard to find parts lately like door internals so need to tick that off before I can relax!


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