TR2/3/3A WHY IS MY TR3 CHOKE CABLE SO HARD TO PULL

[Got_All_4]

I heard some talk on here before about hard to pull TR3 choke cables. I am now experiencing the same thing after fixing a zero jet travel when setting the choke. It just showed up after putting the car away last winter and wanting to get it out last week end. I discovered that the pivoting holes on the jet levers were worn to a 1/4" hole and that slop was being taking up by the travel of the choke cable. It was one of those get r done projects because I wanted to drive it so I took the jet levers off and brazed the now worn 1/4" pivoting holes and re drilled them to 7/32". Lubed everything up and now the jets drop nicely but only after taking 2 men and a boy to pull it out. I should add that the first 1" comes out fine. It's the rest of the travel to get the jets to drop that gets so hard to pull. Before I order new jet levers could there be something else I'm doing wrong?

 

[DNK]

Don't know what is causing the tough pull,but an en easier way to help it push the go pedal down a little while you pull the choke. Have heard it helps.

 

[TR3driver]

First question is, do you have the linkage assembled properly ? The front clevis is not supposed to straddle the lever.

With the cable disconnected, what happens if you try to pinch the two points in the linkage (one for the cable end, other for the cable housing) together ? You should be able to do it easily with just thumb & forefinger.

Did you try replacing the springs, both the return springs on the levers and the gland springs inside the jet housing ? It's not unusual for people to try stretching the jet springs to stop the seals from leaking, then snip links out of the others to get the jets to return.

Which leads to the next question, do the jets return OK once they're lowered ?

One thing I found helpful was to remove the jets and polish them to a luster. Original jets were shiny, but the replacements aren't.

 

[Dave Russell]

--- I discovered that the pivoting holes on the jet levers were worn to a 1/4" hole and that slop was being taking up by the travel of the choke cable. ---- so I took the jet levers off and brazed the now worn 1/4" pivoting holes and re drilled them to 7/32". Lubed everything up and now the jets drop nicely but only after taking 2 men and a boy to pull it out. I should add that the first 1" comes out fine.

A couple of the levers have intentionally oversize holes. This is to give some free play so that the first part of the pull only advances the fast idle cam without lowering the jet. Slop in the levers taken up. Additional pull will then lower the jets for "choke" mixture enrichment for cold starting.

The parts need to be adjusted so that the first part of the pull operates the fast idle cam only. Cam adjusting screw set for about 1500 rpm with the chokes fully pulled.

The next part of the pull lowers the jets for enrichment against the jet return springs. First part of the pull increases fast idle only. Easy pull. Remaining part of the pull advances fast idle further while also lowering the jets. Harder pull.

If you tighten up the lever holes to remove the intentional free play, the fast idle & the jet lowering happen simultaneously. Makes it impossible to set fast idle independently of choke enrichment & makes the linkage bottom out before full jet lowering is achieved.

When the cable is partially released, unchoked, the jets should return fully upward, the fast idle partially released, & when the cable is fully released the fast idle is fully released.

If set up correctly, there should be enough overall choke wire travel to accomodate both the fast idle travel and full jet lowering travel. Check the parts for binding with this described operation in mind.
D

 

[sp53]

Well the choke setting on a tr3 is challenging. I have never been able to just pull the choke out easily with my thumb and finger. I use two hands then push the gas down some and pull pretty hard then turn the choke knob to lock it in the desirable spot. Like Dave said the holes are supposed to be big so the system does not bind up. I like what Dave said about the two stages in which the idle can be raised alone. However, I have not been able to get mine to do that, but I keep trying. Anyways, If you have Moss part number (24) 370-980 flipped around the choke will need the 2 men and large boy to pull it out because it will hit on the carb when it tries to come down

 

[Twosheds]

The Blue TR3 has had hard starting from cold for years and years. It would not start without the use of starting fluid.

Turns out that pulling the choke knob did nothing but take up the slop in the system. When I adjusted all the slop out, I couldn't pull the knob.

On my old TR3 racecar the rear carb choke was disconnected by a PO. The knob pulled easily and the car started instantly with only the front carb "choked" (of course we all know it's really a starting enrichment system).

So I disconnected the rear carb choke on The Blue TR3.

<span style="font-style: italic">Voila!</span> The Blue TR3 now starts instantly. No more starting fluid!

This fix might not be suitable for <span style="font-style: italic">concours d'elegance</span>, but it works.

 

[Got_All_4]

Dave

What size hole should I drill? The pins are 3/16" and I drilled a 32nd over size knowing they are to be slightly over sized. The holes I filled were huge. I swear a 1/4" bold could have gone through it.

 

[Dave Russell]

I don't have a carb off to measure it. There is a lot of free play though, more than you would expect. I hope someone can measure a carb for you.

The size is fairly critical as mentioned. Too large & not enough choke action, too small & vs.

John's idea of using only one choke sounds interesting if you live in a climate that is warm enough to allow starting on one choke.
D

 

[NutmegCT]

Here's some closeups for you (thank you Harry Ward!):

https://www.britishcarforum.com/bcforum/u...e/1/Main/26806/

I had exactly the same symptoms. I did *not* braze the linkage holes, as I knew the play was required for proper action.

After following all the suggestions as listed above, there was marked improvement. New seals, new cable, correct assembly, etc.

But the biggest improvement was when I discovered that one jet was actually bent. When I pulled them to polish the surfaces, I laid them on a table. One actually rocked back and forth - not what you want from a straight pipe!

Put in new jets, polished and lubed. My choke and cable now work properly - but never would have been fixed without the suggestions of BCF members.

Note the comment about the first "half inch" of cable pull. That only moves the fast idle cam to increase idle speed - it isn't supposed to lower the jets at all.

Tom
PS - do an advanced search in the Triumph forum using "choke" as keyword and "nutmegct" as display name, over two years. You'll find all the gory details.

 

[NickMorgan]

Now Tom, wasn't it you who suggested I should take my jets out and grease the cork gland seals? I didn't really think it would work, but it did. I had previously been having the same problem of not being able to pull the choke out more than about an inch. With the jets and seals all lubed up it pulled out reasonably easily and the car started first try. That must have been about a year ago and I have noticed that the choke has started to become more difficult to pull out recently. Must be drying out again.

 

[NutmegCT]

Nick - glad to hear you got it working. Just send your payment to my Swiss account.

Reading back over my original "choke cable experiments" last year, I realize how many folks seem not to have their own set correctly. Perhaps because what they have "looks right", and they don't ever use the choke anyway!

Tom