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Graham Harris

Choke hard to pull out

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This is how my TR3A is set up for the choke cable attachment to the clamp under the front SU carb. Notice that it is all to the engine side of the links that pull down the chokes. It doesn't look like logical or "good" engineering, but that's the way that TRA judges state they came from the factory. If you put the "Y" of the yoke on both sides of the vertical part, it will be hard to pull the choke cable knob. Mine is easy to pull out. Both carb chokes are connected.

Edited by Don Elliott

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Don, as you say that doesn't look like it should be off to one side like that but i did wonder why the choke cable retaining pin was so long. That explains it well done thank you.

Regards Graham

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Hello Graham,

The TRA judges and Don Elliott's post are well supported by the photo on page 35 of the Owners Handbook.

Regards,

John

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Read all these "solutions"

 

Dick is on the money, you only need to use the choke on one carb, hence reducing all the worn mechanical areas of resistance.

 

Engine always starts as mentioned,even in the coldest winters.

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I think that the choke was designed before the heater was added. The result is that it has a serious bend round the heater. I improved this by moving the whole thing to the dash by the speedometer so that the cable has a straight run. Now it works well.

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Hi Don ~

Both my choke 'yoke' connection's are fitted centrally on the choke levers and it is as smooth as silk to operate.

Both chokes are connected.

Regards ~

Tom.

Edited by Fireman049

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Tom, I took your advice with the cable, i could not get any graphite grease but i did get some graphite powder(messy stuff) puffed it into the outer and ran the inner through several times then put it all back together. It's interesting to see how Don set his up, which is how it is in the owners manual,i just cant see why they would do that. I'm sure SU Carburettors did'nt intend it to be fitted like that. Anyway i did'nt, well i did try it and i couldn't tell any differance so i put together with the yokes inserted. The graphite on the cable seems to have done the trick it now works fine.

Thanks for all your help

Graham

Edited by Graham Harris

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Graham, I suspect the choke mechanism was put on the inside to keep it away from the adjacent loom on the inner guard. If mounted centrally as commonsense suggests, the front carby choke linkages can (and do) rub through the loom casing.

 

I've only choked the front carby for many years. The cable pulls easily and it always starts straight away. An electric fuel pump helps by pre-filling the bowls.

 

Viv.

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It had HS6s on a TR4A manifold, but I converted it back to standard and rebuilt a pair of H6s a club member gave me.

 

It was running badly and if found the front main jet was down 75 thou. The choke was stuck, so I applied Stuart's ferrule and made sure the choke returned and the jet was 40 thou down. It's running perfectly now, so I'm a happy bunny!

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Assuming this problem is with SU carbs?

Remove enough bits to be able to ease the jet out of the bottom of the carb. Don't damage the cork lining. Polish the outside of the brass jet to a mirror finish (solvol autosol is perfick for the job). Put a light smear of silicon oil on the jet and use a cotton bud to smear the inside of the corks (lifting up the piston to move the needle out of the way) and carefully reinsert the jet into the carb, avoiding damaging the corks. Reassemble. The choke will now operate easily, (assuming you haven't stretched the return springs?) and will always close fully, ensuring the fuel/air mix remains stable. You can now set up the carb to the manual.

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I'm fairly sure that there are jet return springs with different rates of "pull". The weeker ones for multiple carbs. Had a look in my SU bits box and there are definitely two types.

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I totally agree with the choke being notoriously hard to pull out on these cars (TR3). I disconnected the rear carburettor linkage, and it works fine with the front choke only. To operate it is much lighter and the car starts even in cold weather, not that the temperature is that cold here in Malta. Photo attached .

Thanks for the help.

 

Regards

Pete

post-15310-0-40510300-1512547922_thumb.jpg

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I've solved my problems - in addition to the really tight choke, I have had weeping fuel from the bottom of the jet, and an ever richening mixture, and changed the corks three times, but it just kept coming back.  I think the cork seals are not up to Ethanol?  Anyway, I have found PTFE 'o' rings that are the perfect fit.  PTFE was the only material I could find that was 100% immune to both petrol and methanol.  I doubled up with the ptfe 'o' rings, two at top and two at bottom, and what an amazing, instant fix.  PTFE being self lubricating and with a coefficient of friction close to wet ice, the choke slides in and out with ease, and there is not the slightest wiff of petrol.  Happy days.

If anyone wants further details of 'o' rings, contact me at david@dsaelectrical.com.  If there is enogh demand we should be able to benefit from economy of scale.

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