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Correct Choke Cable Run


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Hi,

 

The choke cable on my 4A ran from the lower bulkhead.

 

However, nearly all of the pictures I see of the SU carb installations have the choke cable running in from the top of the carb which means the choke cable needs to run from the upper bulkhead.

 

The picture is of my current set up and the choke cable is just resting in there at present.

 

This would mean the choke cable would touch the bonnet when closed.

 

I guess the choke cable originally ran from the lower bulkhead as Strombergs were fitted.

 

As I have SU HS6 carbs, what would be the best cable run?

 

Many thanks.

 

Paul.

 

 

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Thanks Stef - good one.

 

Best

 

Paul.

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Thanks Roger /Michael.

 

I saw a cable that went a similar height to the rocker cover so I'll aim for that - aim:-)

 

Best.

 

Paul.

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Thanks again Stef. Best

Paul.

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  • 5 years later...

Having got the choke cable run sorted with help from the useful comments above (S HS6s), I'm finding that the very expensive (Moss) choke cable won't stay out and is very stiff to operate; any ideas on how to rectify this? I did trim the cable down in length slightly so there wasn't such a large loop under the bonnet.....

Rgds

David

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Hi David,

 the choke cable has a single steel inner core. Generally the bigger the loop the better. It wants to run in a straight line.

You say that the cable will not stay out. Assuming that the new cable has all its internal parts then have you tried to rotate the knob through 90 degrees having pulled it out. 

It works in the following manner - the central steel core is attached to a solid brass rod that has wedges cut into it.

These wedges lock onto a spring loaded piece of metal to hold it into position. To release simply rotate 90' and push.  Yours may have a twist on it

keeping it on the unlocked condition.

The mechanism can be quite stiff but should relax given time

 

Roger

P1020340a.jpg

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Thanks Roger, my new cable has the notched central piece and a multicore cable (like a bike brake cable), I fear I might have chopped it a little neat, however the choke doesn't stay out even when twisted 90 deg. Does anyone sell them with a solid core? (and the correct knob attachment)

David

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Hi David,

 the solid core is not important.

If the knob does not stay out then there is a possibility that the little 1/2 moon plate that locks into the wedges may be missing  :o

So remove the cable and remove the black circular springy clip. This should reveal the 1/2 moon latch.

Should it not be there (heavens above) it is possible to remake so  that it will work.  It should probably be made from a slightly hard steel but start with a piece 

of hacksaw blade ground to shape.

 

As an aside, how well does your choke cable fit with regard to interfering with the heater box.

Both my 4 and 4A had the same issue. The cable hit the box and would not come out straight at the back of the dash. 

This could make the operation a bit stiffer!!.   See my attached picture. I cut a slot in the air chamber and the sealed it.

The choke now has a straight run

Roger

P1060791a.jpg

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14 hours ago, RogerH said:

Hi David,

 the solid core is not important.

If the knob does not stay out then there is a possibility that the little 1/2 moon plate that locks into the wedges may be missing  :o

So remove the cable and remove the black circular springy clip. This should reveal the 1/2 moon latch.

Should it not be there (heavens above) it is possible to remake so  that it will work.  It should probably be made from a slightly hard steel but start with a piece 

of hacksaw blade ground to shape.

 

As an aside, how well does your choke cable fit with regard to interfering with the heater box.

Both my 4 and 4A had the same issue. The cable hit the box and would not come out straight at the back of the dash. 

This could make the operation a bit stiffer!!.   See my attached picture. I cut a slot in the air chamber and the sealed it.

The choke now has a straight run

Roger

P1060791a.jpg

Thanks Roger, I remember that project, but I was beyond that point when you posted it and I didn't have the motivation to take out the heater box and chop it up; brilliant though the idea is! I'll investigate the 1/2 moon clip and report back :)

Rgds

David

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Ok so I removed the cable as suggested and there is no half moon plate evident; I also noticed that every time I pull the choke knob out and back in there are some fine (brass?) filings deposited on the plinth! To answer your question Roger, the cable routing is as shown below, the bends don't look too serious to me, however if you see the second phot with the cable route to carb, I fear I may have cut the cable too short to avoid the bonnet rubbing and created a bend just as it enters the carb hole-thing. You will notice that my cable goes to the front carb rather than the rear as normal, this is because these HS6s were originally off a TR7 before being refurbed and reconfigured by Andrew Turner.

So I guess I'm at the point of 

a.  ordering another £70 cable from Moss

b.  buying a cheaper twist/lock cable (I'm not too bothered about originality if the thing works properly)

Any suggestions?

Rgds

David

choke cable run.JPG

carb linkages2.JPG

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Hi David,

 obviously the lack of the half moon wedge plate is the cause of the cable not staying out.

The half moon plate would certainly generate some brass filings but as it is not there then !!!!!!

Does the rear carb not have any possibility of holding the choke cable - your set-up doesn't look right.  Any chance of a Photo from above showing both carbs.

 

Roger

Edited by RogerH
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I'm just missing the hollow tube that sits in the carb body that the choke cable sits in, are they removeable?

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also the triangular plate that locates the connecting rods, I'm not sure mine is the right way round although it looks kinda right and it seems to work. I've seen phots with it flipped around the other way but then the connecting rod to the throttle linkage looks to be at an awkward angle

Rgds

David

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I have HS6s on my 65 TR4a, that were added by the PO, and the choke goes to the rear carb. Also I believe since the early TR4As didn’t have HS6 carbs, the choke cable originally routed from a lower hole in the bulkhead, below the carbs. When HS6s were fitted later, which receive the choke cable from above, a new bulkhead hole was added up by the heater hoses, so the choke could be routed from above.

Jim

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The cable should go to the rear carb originally, see below pictures.

Stuart.

 

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6332616298_1b16e35d25.jpg

IMG_1596.JPG

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4 hours ago, RogerH said:

I'm sure they are available from somebody like Burlen's.  But I would not be surprised if it simply pulled out.

 

Roger 

Ok so I've tried gently pulling it upwards and tapping it downwards; absolutely doesn't want to move. I've looked at every SU Carb diagram I can find and they all show that hollow tube as part of the carb body and not sold as a separate part. So unless anyone has a suggestion I think I'm stuck with the front carb location - not sure it makes much of a difference??

Rgds

David

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