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TR2/3/3A TR3 choke cable woes

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CraigLandrum

CraigLandrum

Jedi Hopeful
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OK, carbs are tuned and throttle linkage back on, but for the life of me I can't seem to get the choke cable hooked back up in such a way as to be able to be operated by a human.

- Its a new choke cable from Moss
- New choke linkage rod and cable attachment pin
- I'm pulling the mixture rods back to take out the slack (like tghe book says to do), just to the point that any more would start changing the mixture, then I tighten the cable
- The cable seems to work smoothly when not hooked up, but once its is hooked up, seems to require way too much pull, and the rods barely move on the carbs - not even close to full travel. The required pull to get even as far I get is such that I'm scared I will break something if I use more.

The carbs are tuned up and engine runs smoothly, mixture is not too rich, not too lean.

The cable casing gets clamped to an extension arm at the point the actual cable emerges from the casing at the end. The cable then extends out for about a couple inches or so and then gets threaded through the hole in the pin that goes through the mixture rod coupling.

When we installed the new choke cable we cut off surplus casing from the end of the cable to get rid of a bunch of slack that hung down inside the cockpit under the dash. Could we have cut off too much, thus making the cable bind under the tension that occurs when you pull on the knob?

FYI, the carbs were rebuilt - could something have gotten overtightened?

Any suggestion or insights would be welcome.
 
Hi Craig. Same thing happened to me. Took two feet against the dash and both hands on the knob to get the cable to pull. Here's what I did to fix it:

- checked to make sure I could lower the jets by hand without them binding (that determined the hang was the jets, and not in the cable or linkage). The jets were indeed very tight.

- removed and polished the jets (I used toothpaste, but don't tell anybody ...)

- put vaseline on the seals

- re-attached and re-adjusted the linkage, to make sure the first "inch" of cable pull only activated the cold idle cam and did *not* start to pull the jets down

Hope this helps. I'll scout out my original thread on this for you.

Tom
 
OK - rather than posting a gazillions links, just do an Advanced search over the last 2 years using "choke" as the subject <Keyword> and "NutmegCT" as the display name. You'll see what I mean about lots of solutions, and you're not alone.

I think the first step would be to determine if those jets slide up/down just using finger pressure. Mine were way too tight, due to (1) tight seals, (2) need to polish, and (3) one jet was actually bent. Once I got the jets to slide by themselves, I hooked up the linkage and cable and all worked fine.

Tom
PS - you probably already know it's not really a true "choke"; it's an "enrichening device". Lowers the jet to allow more gas to enter the carb. I just barely need to use mine even in the coldest weather. It's the cold idle cam setting that's more important in that hookup, at least on my TR.

PPS - this might help if you have any question on the linkage or the cable routing:

Carb%20Linkage.jpg
 
Craig,
Do what Tom says! I remember trying to help him out with his choke problem a year or so ago. Turned out that I had the same problem with my car (which went some way to explain why I had been having difficulty starting it!). I took Tom's advice, stripped out the jets, greased the cork glands and now my choke works.
I remember that there was also some discussion about the pros and cons of rubber versus cork seals.
Nick
 
Ask Nick notes, one of the concerns about using o-rings as a jet seal in lieu of the cork seals is that they may bind and hold the jet firmly in place. The use of a silicone o-ring usually solves the problem allowing the jet to slide freely.
 
I believe I used the rubber o-rings when I rebuilt the carbs. I think I got the kit from TRF.

I didn't do anything to the jets themselves, nor did I use any sort of lubrication during assembly, which may be why it's so stiff. It's difficult to move the choke linkage by hand, so I suspect it may be binding at the jets.
 
OK, you guys are probably smarter than I, but for years I suffered from a difficult to pull choke on my TR6 -until someone on this forum pointed out that I wasn't using it correctly. The key has to do with the fast idle cam. If I first press the accelerator down a little, the pressure on the cam is removed and the choke pulls out easily. This may not be your problem, or you may have another, but I was so shocked by this information I ran out to the garage and tested it. Now, every time I pull the choke out, I can't believe how I used to struggle with it.

I wish my project was coming along as well as yours -but I haven't seen any pictures for a while.

Jerry
 
I was having the same problem with the choke on my car. Very tight, I need both hands to pull it out.

Right after I bought my car I noticed the front carb was leaking badly so I took the jet assembly out and found that the cork seals had just about disintegrated. I reassembled it with a new cork seal for the gland nut and O-rings for the jet and did the same thing, I didn't lube anything when I put the jet back together.

A few weeks ago when I ran up my car I noticed that the piston on the rear carb was sticking which meant I need to centralize the jet for that carb. I've been having a issue with the floats weeping small amounts of fuel where they attach to the bottom of the carbs. So I figured now is as good a time as any to replace all of the seals. While I was taking the carbs apart I noticed the jet on my front carb was very tight, it was so tight the jet return spring wasn't strong enough to pull the jet back up.

Doing some research I found a very good video on YouTube that John Twist of University Motors has done on how to centralize the jets on a H6 carb. What caught my eye were few things. He only used the cork seals and soaked them in oil also he lubricated everything with oil when he reassembled the jet. After he was done he operated the jet and it moved up and down very smoothly with out any resistance.

Personally, I think the O-rings are too tight and offer too much resistance on the jet and hinders smooth operation. I'm going to use just the cork seals and soak them in oil and lubricate all of the parts of the jets when I reassemble my carbs.
 
A few more things that will help, IMO :

1) Polish the surface of the jet until it shines. The original jets were supplied slick, but newer replacements have a much rougher (more abrasion = more friction) surface. This will also lengthen the life of the seals.

2) It's very common to find that a DPO has stretched the spring that applies pressure to the jet seals, in an attempt to stop the cork from leaking. If there is any doubt, replace the spring.

3) The choke link between the carbs is NOT supposed to straddle the levers. Instead, both legs of the link go behind the levers. I know this sound strange, but it really does work better that way.

4) The choke cable should be stranded, not solid wire.

5) A drop of oil on each of the pivot points, once a year, will help too.

BTW, I had the O-rings from Moss on TS39781LO and loved them. Last much longer than the cork rings; and I did not notice them making the choke any more difficult than with the cork. My technique is to brace one finger against the dash while pulling the knob, mostly to avoid too much stress on the dash. Doing that, I can pull it with one hand. Depressing the gas pedal is optional (but does reduce the force).

PS: I have also seen people trim coils from the return springs, to get them to return after doing (2) above. Again, if there is any doubt, just replace them.

PPS: Make sure that all the joints are free. I've also seen people use bolts instead of pins, to try to remove some of the 'slop'. Bad idea, the slop is supposed to be there.
 
NutmegCT said:
Randall - did you do any lubrication on those o-rings or other jet parts? Vaseline, etc.?
Click to expand...
I've tried that in the distant past, but it didn't seem to make any difference. The jet is bathed in gasoline constantly, which will quickly wash away Vaseline or any petroleum based lubricant, IMO.

Oh yeah, lubricating the cable also helped. Vaseline would work there, but IMO a dry lubricant like graphite or dry moly would be better. ISTR mine is full of powdered moly, but I didn't even pull it apart before moving it from the 3A to the 3.
 
I removed the control rod and choke the front carb only. I use a stranded choke cable. The jet returns to its proper location when I push the choke knob in. The car starts fine the choke knob is easy to pull.
 
When I rebuilt my carburettors I used cork seals and glands as original. I soaked them for a day or two in oil and actually heated the oil on the stove thinking that it may have helped the oil to soak in better (I wasn't married then!)
The oil seems to have gradually dried out, possibly by being diluted by petrol. Of course I keep forgetting that I rebuilt much of my TR about 18 years ago! I think that the oil actually lasted about 12 years, so can't really complain. A year or so ago I dismantled the jets and greased the cork glands and they are now operating easily again.
 
Just my opinion, but IMO if you can drive smoothly with the engine cold and only the front carb choked; your mixture is too rich.

I even have trouble with stumbling on cold acceleration just from the chokes not being synchronized. Definite problem for me, as my commute to work involves a left turn across 3 lanes of fast traffic less than 100 yards from my driveway.
 
This has been a most informative thread.

cam.jpg


I've got the TRF choke knob/cable but can't seem to get it right:

Pulling the choke knob to the first stop (3/8") only takes some slack out the system.
Pulling to the second stop (3/4") lowers the jet on the front carb by approx 1/8" but doesn't move that cam enough to lift the throttle lever.

I've taken as much slack out of the cable as I can, fiddled with the bolt holding the cam and messed with the gap between the cam and the spring-loaded screw. No joy.

Any ideas?

Cheers,
Adrian
TS58325
 
Well, what does the front lever do when you first start to pull the knob?

The lever should have an oversize hole where it is attached to the bracket (the two pieces that also extend down and grip the outside of the choke cable); so that when you start to pull the cable, the rear of the lever moves upwards without pulling the jet down. That motion should be enough to move the fast idle cam.

A photo of the jet & linkage, first with the cable all the way in, and then with it pulled just to where it starts to lower the jet, would help.

I'd post some photos of my own, but I need to head out in the dark & cold to look for a windshield buffer. I know I've got several but can't seem to find any of them in the garage, so I'm headed out to the shed.
 
My son and I went back and attacked the choke cable. I removed and polished the jet from the front carb so it gleamed, gave it a bit of lube and reinstalled it. Hooked it back up to the arm and with no cable or spring attached verified that the arm, when pulled, could easily lower it - light one-finger pressure. Felt right. Started to pull the rear jet when and give it the same treatment when I decided to try it without the spring. Worked fine with light one finger pressure. Hooked up the spring, and it became like glue. Same for both carbs.

Tried hooking all linkages back up and attached the cable with no springs and fast idle cam screw raised to eliminate the effect of the throttle spring. Choke could be pulled easily and jets lowered.

Our carb springs are new and our throttle return spring is new. Lots of resistance and spring in both, and when you add up the effect of those two carb springs and the throttle spring, there simply isn't a prayer that the choke cable will be able to pull those jets.

So - since the car actually starts quite easily with no choke action, I adjusted the fast idle cam screw that lifts the throttle a bit when you first pull on the choke cable ( helps to push down the accelerator pedal a bit to eliminate the effect of the throttle spring). This at least lets me feel like I've got a choke cable that does *something* (increases the idle speed a bit). Unless someone tells me that the new springs they sell for the carbs are the wrong ones, I'm just going to give up on ever having the choke cable lower those jets, because I cannot see how that cable can ever overcome the pull of those springs.
 
All I can say is it shouldn't be that way, Craig. It sounds like your new springs are too stiff.

I just ordered some genuine SU springs from TRF. Maybe later next week I can take some measurements on them. But they should be weak enough that it's not too difficult to spread them slightly, just holding the loops between your fingers.

Where did you get your choke return springs?
 
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