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Throttle Return Spring, Extended Length At Idle

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#1 PaulWright

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Posted 27 March 2013 - 01:54 PM

Hi

I recently fitted an RC40 exhaust and a freeflow manifold to my MkII mini. Before the change, the throttle return spring was attached to the exhaust pipe clamp using a tag like this: http://www.somerford...7VyhA5Pxnp9fft1

With the freeflow the exhaust clamp no longer exists, so I can't attach the tag as it used to be. To get round this I attached a standard U-Bolt exhaust clamp on the freeflow giving me a bolt to hang the tag.

But having lost the old exhaust and manifold (it got nicked from my drive) - I don't know how far down the manifold pipe the U-Bolt clamp needs to go, to give the spring the right tension.

So my request is that if anybody happens to have the head under the bonnet could they kindly measure the length of the return spring (at idle). With this information I can move my U-clamp to the right place.

NB my carb is a single HS4 with the throttle controls on the left hand side(looking into the engine). Most HS4s have the controls on the right and would use the normal abutment plate rather than this tag.

Many thanks

Paul

#2 jaydee

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Posted 27 March 2013 - 02:18 PM

The tag is for the HS2 carb
Sounds like you have the right hand type HS4..you cant use the abutment plate the wrong way round it will catch the exhaust and (minor problem) you wont be able to use the airbox.
Anyhow I have a car with standard HS4 setup in the garage and cant take measurement if you need to fabricate your own bracket

#3 ANON

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Posted 27 March 2013 - 07:38 PM

get a torsion spring on it, the normal spring is what kills the hs4.

#4 jaydee

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Posted 27 March 2013 - 08:07 PM

Very true, the big side spring is what causes the wear on the spindle bushings on the HS4, HS2 and HIFF carbs with the different spring are less prone to that problem.
by the way the spring at idle is about 12 cm with the normal abutment plate

#5 Chance

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Posted 27 March 2013 - 08:10 PM

What is this torsion spring we speak of..

I have a HS4 with normal sprin..this is bad??

#6 PaulWright

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Posted 28 March 2013 - 10:18 AM

Many thanks for your replies.

I'll work with 12cm extension at idle.

The torsion spring is an interesting idea, I did not consider the wear on the spindle (obviously Austin/Morris didn't either). Any advice as to go about making the conversion, spring size etc.?

Cheers Paul

#7 tiger99

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Posted 28 March 2013 - 11:33 AM

If the spindle wears, the body can be reamed to take readily available bushes, so it is not a great disaster. But the torsion spring does indeed sound interesting. I assume that it would be like a clock spring, as there are various types of torsion spring, and that seems the most practicable here. It would be advisable to ensure that two independent springs were fitted, as you can imagine what happens if there is only one, and it breaks! I believe that most forms of motorsport have rules which require two springs, and it ought to be the norm on road cars too.

It seems to me that it would be a fairly simple job for someone with access to a lathe and milling machine to make an extra-long spindle, with provision for a spring at each end. Or perhaps you would not need to, because twin SU setups on some cars used double-ended spindles.

Edited by tiger99, 28 March 2013 - 11:34 AM.


#8 cal844

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Posted 28 March 2013 - 12:53 PM

i need a return spring but cant find one on the usual sources, could anyone advise where i could get one? car is an 89 998 with(i believe) an hs2

#9 ANON

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Posted 28 March 2013 - 10:22 PM

just phone burlen





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