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Stiff choke mechanismn


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I have been trying to fix my choke mech so it doesn`t need 2 hands to pull the knob out, I have routed the cable as directly as I can to avoid kinks. When disconnected the piano wire moves easily inside the outer cable, but as soon as connected it is back to being almost impossible to pull out. Am I alone in this, I can`t believe they were like this when new.

Ralph

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The inner should not be "piano wire", it should be a stranded cable (like a bicycle brake cable).

This may be the problem as there is a sharp bend at the end of the tube behind the knob where it grazes past the heater.

Otherwise look at the choke mechanism on the carburetors, maybe one or the other is very stiff to move.

Bob.

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2 hours ago, Ralph Whitaker said:

I can`t believe they were like this when new.

If it's any comfort, mine is like that too. 

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Make sure that each choke mechanism pulls correctly and that there is sufficient play in the whole lot as if you take all the slack out it makes it worse, as Bob says piano wire inners dont help and make sure the link between the carb chokes is connected correctly at the front one too.

Stuart.

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Another area to check is the jet lever or rod link to the cam. If the cam isn't positioned  at the correct angle then the link is too vertical and it is very difficult to pull the choke as the lever can't push the cam upwards. I am forever playing around with the positioning of the cam between been able to pull the choke easily and achieving the correct tickover! 

Rob

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Mine is piano wire too and requires two hands. 

Mine is turn to lock rather than the OE ratchet type which has a very long rigid outer casing at the dash. The original longer rigid tube points the flexible bit straight at the heater.  The turn to lock one I have has a rigid tube maybe 1/2 - 2/3 length of the ratchet type, so the flex easily routes round the heater.

I sourced and sold a lot of choke cables like that back in the early 1980's so maybe that is where yours came from Ralph.

Peter W

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Mine is an original (? I've never replaced it in 40 plus years) Piano Wire and was an absolute swine. The stiffness was in the mechanism not the wire. In discussion with Martin Jay ( Dizzy Dr) he gave me a tip to try and it worked. Clean and grease the front choke mechanism with a High temperature grease......no more issues, moves freely and locks in position.

Iain

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Mine is also ridiculously stiff and apparently this is not unusual. Luckily I dont use it very often. A big part of the problem seems to be the jets binding in the carbs and the Rube Goldberg operating mechanism isnt efficient enough to overcome it. One approach seems to be to disconnect one of the carbs (front ?) as that will still start the engine on a cold day but will be easier to apply the choke. On the few occasions that I need to start the engine in the winter I operate the choke as usual then open the bonnet and pull the jets down by hand.

Stan

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16 minutes ago, foster461 said:

 One approach seems to be to disconnect one of the carbs (front ?) as that will still start the engine on a cold day but will be easier to apply the choke.

Stan

If your going down that route you disconnect the link arm from front to rear so your still operating the fast idle mechanism on the front carb.

Stuart.

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Thanks Guys, lots to consider there. I took the inner wire out tonight and straightened and greased it, and it is now marginally better. Mine is also a turn to lock, a spare from my vitesse. I think I will try greasing the linkages next.

Ralph

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  • 2 weeks later...

I have mine working well. 

  1. It is a simple straight wire , bike cable , running from a new position near the speedo and heading straight for the front carb only. The original switch position is now in use for the spot lamps
  2. It is fixed to the front jet lever and pulls down easily with one hand. It returns to normal position by using a small spring which pulls it back, which is always there, attached to the front inner wing.
  3. The car always starts now however  cold the weather may be. I used to have problems for decades in the cold weather.
  4. The outer cable was loose and it looked untidy. So I fixed it to the front jet lever which was still there but not working. This made it look correct but I was back with two hands.It was strange that such a small alteration could make so much difference. It is definitely much easier if it is left loose

In the old days if I used it all through winter it was an embarrassment every night., Now that I have it working well there are many weeks when  it is not so cold and it is not in use anyway. BUT it starts in Winter.

Good luck Richard and Bruno

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Mine is fixed to the metal dash and not in the centre panel. Makes removing the centre panel easier and straightens out the wire run. The hole where the choke used to be now used for my windscreen washers.  It has placed the choke knob slightly behind the wheel which does not help access, having to put one hand through the wheel and one hand behind the wheel to get sufficient pull on the choke knob.

Ralph

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3 hours ago, Richardtr3a said:

After so many answers, I disconnected my outer cable lat night. The inner now only needs one hand .very light pull and it is now working very well.

Good luck

I would have to shorten the outer cable, otherwise applying the choke would simply move the outer cable until it contacted the clamping nut of the inner cable.

Ralph

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