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TR2/3/3A choke operation from the factory !!!!

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sp53

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Well I have been burning out my eyeballs out trying to find a picture and instruction on how to operate the choke. The stuff I have learned over the years is to twist the knob to the right, pull the choke knob out then twist back to the left and release the choke; let it catch on one of the groves in the choke mechanism. When the motor has warmed up some, turn to the choke knob to the right again and then push the choke in and turn to the left until the choke catches on the next grove; let the engine warm up some more turn the choke to right and push in and then turn back to the left until the choke stops on the next grove or is fully returned with a warm engine and with the words CHOKE facing up.

There seems to be 2 catches on the chokes I have used before I run out of pulled cable and the engine is warm and the choke has returned.


I looked in Bentley and the practical hints, but could find anything.


In addition, to this I was looking for those little brass clips the choke cable anchors down with under the dash by the glove box.


Has anyone found any information on choke operation from the factory !!!!

steve
 
Steve - the choke info is on page 11 of the Practical Hints booklet.

If you're following those instructions and something isn't right, it may be that your choke (the mixture enrichment mechanism) needs adjusting.

Tom M.
 
Problem is, page 11 doesn't describe exactly how to lock and unlock the cable. It implies the cable will lock in the outer position without being turned, but then says to turn it to lock in the intermediate position. But not to turn it to return fully home. And it doesn't say which way to turn to lock it.

Frankly, I just don't remember exactly how the original cable worked. I've been running an aftermarket cable since 1984 or so, and it will lock if turned in either direction.
 
My recollection is that it will lock at any of the stops when pulled out and you twist it (CCW?) to release.

Of course many have lost that tiny crescent moon piece that engages the stop (it falls out if you pull a detached cable out very far) at which point a wooden spring-type clothes pin becomes the tool of choice for holding the choke in the start position.
 
" ... at which point a wooden spring-type clothes pin becomes the tool of choice for holding the choke in the start position."

I remember using two of those clothes pins for full choke on my TR3, then removing one for "high speed idle". Memories, memories.

Tom M.

 
My choke is working fine. I just wanted to see what the book says. It took many years to get a choke system that I figured the book expected me to use. When I got my first tr3 in 1971 the guy told me to use a bent bottle cap that he himself had bent just right. I have put those little clips in Geo. Once it is done a few times it gets easier. I find the actual length of cable coming out of the sheath and the slight preload on the carburetor arms critical for proper adjustment. Plus the correct anchoring for the cable under the dash is key.

I was going to leave the car with my son while I go on a long business trip and wanted him to have a guide on starting in case he forgot my overwhelming instructions. IMHO the choke is one of the chief reasons why back in the day and today also--- these cars went tits up and were parked alongside the house with 47k miles new. Heck it is easy to get half the engine running way different than the other half if the choke is wrong. Then people start turning other screws to fix the engine.
 
sp53 said:
IMHO the choke is one of the chief reasons why back in the day and today also--- these cars went tits up and were parked alongside the house with 47k miles new.
Click to expand...
When I bought my previous TR3A back in 1983 (a birthday present from my late wife), I was told that the owner had spent a lot of money trying to get it running, but it still wouldn't start. He had left it in a friend's shop and I only dealt with the friend. I turned the key then grabbed the choke levers in one hand and punched the solenoid with the other; it fired right up. The look of amazement on the shop owner's face was priceless! He said the car obviously liked me, we were meant for each other, and dropped the price another $500! I drove it home.

I bought an aftermarket choke cable from Moss that had the wrong knob permanently attached, but a much more effective (and durable) locking mechanism, all in steel. It's still in use today, as I moved it from the wreck to my current TR3. Sanded the knob down a bit, so it doesn't look too badly out of place.
MGKPVaJ.jpg
 
Well, the driver won't lose weight, and it has to come off somewhere !

Besides, with the front wing seals missing, the vent doesn't do much anyway.
 
The SU choke is what is usually referred to as an “enricher” as it never chokes anything. So our nomenclature is off at the start! How can you follow an instruction manual that begins right off the bat with the wrong term for the device? My old Harley’s use the constant velocity carbs just like our SU’s. Harley calls it an enricher. You pull it out all the way to start, and then work it in as it warms, so the engine runs smoothly the entire time.

That said, the SU choke cables I have encountered can be pulled straight out to the stop without twisting the knob. You hear the ratchet clicking as you pull. To release the ratchets, you have to twist so the word “choke” is crooked. If you want to stop part way...you simply put it where you want it and turn it straight to lock.

I think most choke issues stem from sticky jets and cables. Either you can’t pull them out easily...or they stick when pushing the knob in.
 
I like the old British term "strangler" for the choke. The term have been used in this country as well, and it aptly describes what I felt like doing to the S.U. designers when the TR wouldn't start on New Hampshire winter mornings.
 
I think I am probably babying my clicker by twisting first because I have had so many clickers break and by first turning everything is smoother. I guess I could pull straight out, but I feel the resistance and turn to the right so I can easily one hand it and then find the next grove/click. Interesting how you find a spot between clicks John. I can but the general vibration of the engine lets the mechanism slip down to the next click, so I am basically stuck with 2 spots for warm up.

I am not sure of this, but I think it is true; the early chokes did not say “CHOKE PULL” they just said “CHOKE”. Another point that is interesting about the original chokes is that the nut holding the cable to the back of the dash was brass. I think this is the case because the choke is like a ground strap for the engine to the tub.
steve
 
sp53 said:
Another point that is interesting about the original chokes is that the nut holding the cable to the back of the dash was brass. I think this is the case because the choke is like a ground strap for the engine to the tub.
steve
Click to expand...

Interesting thought. We’ve had 2 restoration projects on the forums that apparently were so well painted that the body bolts did not ground the tub to the frame. I never thought about it, but the choke is the only all-metal positive connection between the 2. Funny cars...!....just like when I discovered that the gas sender is supposed to be grounded through the braided fuel hose that goes into the fuel pump!?!
 
This is the first time I've ever heard that you're supposed to twist the choke knob. I just push mine back in. Is something wrong on mine? Of course it's a beast to pull out. Sometimes takes two hands. Barely have to touch it to push it in.
 
CJD said:
...so well painted that the body bolts did not ground the tub to the frame. I never thought about it, but the choke is the only all-metal positive connection between the 2...
Click to expand...

I believe there should be a braided ground cable from the LH motor mount to a timing cover bolt (and of course the battery is grounded to the body). If the choke cable was the only ground to the engine it would glow red as you cranked the starter.

BTW, the speedo cable will also serve as an engine ground if the braided cable is missing - it will also heat up with possibly disastrous results for the hairspring in the unit.
 
I thought there was a second ground wire at the tank sender that went underneath one of the tank strap bolts John?
 
Geo Hahn said:
I believe there should be a braided ground cable from the LH motor mount to a timing cover bolt (and of course the battery is grounded to the body). If the choke cable was the only ground to the engine it would glow red as you cranked the starter.
Click to expand...
Yup, I've seen it happen! So no, those other paths are not intended as grounds, they just didn't have sophisticated plastics back then so metal was the material of choice.

No idea why someone chose brass for the nut, perhaps for corrosion resistance. Several other things were brass on early cars, like the door hinges.

Here's a shot of the engine ground strap (photo courtesy Don Elliott)
VRYaQOB.jpg
 
Snowkilts said:
This is the first time I've ever heard that you're supposed to twist the choke knob. I just push mine back in. Is something wrong on mine? Of course it's a beast to pull out. Sometimes takes two hands. Barely have to touch it to push it in.
Click to expand...
Yup, sounds like that little brass piece is worn out or missing. The notches on the shaft wear over time too. I've had some success in the distant past with manufacturing a replacement piece, but I forget the details offhand (like where I got the brass stock).

I've seen several carbs where someone has stretched the spring inside the jet housing, in an attempt to keep the glands from leaking. Replacing with a new, correct spring can greatly reduce effort required to pull the choke.

Also, original jets were highly polished; modern replacements are supplied much rougher. Polishing the surface to a shine will help them slip through the glands easier (and maybe even help the glands last longer). Polishing compound or even white toothpaste will do for a polishing agent.
 
John, I thought there was a second ground wire at the tank sender that went down underneath one of the tank strap bolts ?
 
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