Some of the posts in Rattle and Smokes 'starting' thread got me thinking. These days most manuals just tell you to turn the key without touching the throttle.
Back in the early '80s, my parents had a '79 Opel Ascona (aka Vauxhall Cavalier) 2.0, which had an 'automatic' choke. It wouldn't start from cold unless you manually depressed and released the accelerator once before cranking the engine. Invariably the choke would stay on way too long as the engine warmed and would require a blip of the throttle to get it to go off. Not very automatic to my mind. A 1983 Mazda 626 2.0 followed this, which strangely had a manual choke. At least this gave you a bit more control and didn't pretend to be automatic. Thinking back, both were carburretor engines and I guess chokes or other petrol engine cold-start aids did genuinely become far more automatic as fuel injection systems became more common.
Both of the fuel injected petrol cars that we now have start from cold without me doing anything other than turning the key.
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The Early E series 1.6 on the maestro had an electronically controlled SU carburettor.
It was complete pants, and had ot have a dose of ezi start every cold or damp morning, and on hot days would suddenly decide to idle at 3k revs.
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I had a MK3 Cortina (coke bottle) GT with an auto choke that gave me no problems. If anyone else drove it...........
I've a Kia Pride (have I mentioned it before?) with an auto choke that ticks over at anything up to 3K RPM as it warms up. I've looked at the carb and decided to leave well alone as it settles down very quickly.
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Early Auto chokes go back to the beginning of the 20th. century.The type mentioned however was a purely mechanical type as opposed to some in which mixture just bypassed the throttle plate.The choke was set by putting your foot on the accelerator-this opened the throttle,allowed a cam to set to up the idle speed,the choke plate closed and also there was a squirt of fuel from the accelerator pump to enrich the mixture.Hi-cam idle speed was normally set to about 2500-3000 rpm with a hot engine-10 secs after starting you were supposed to squeeze the accelerator and this speed would drop to about 1200 rpm and then you drove away normally. Many years ago,I worked for a major manufacturer and we were getting many complaints of poor cold starting-so many that a team was set up to check them out.The team would check the vehicle the previous day to make sure that there was nothing stupid in the settings and then would go to the complainant's house next morning and ask the owner to start his car as spelt out in the driver's manual.Guess what-every vehicle(both vehicles with manual or auto chokes) started perfectly.When all else fails-read the instructions.Also known as RTFM.
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Favourite modification on Fords was to throw away the (Zenith/Solex or what what was it?) carb and replace with twin choke Weber from 1600GT...auto choke disconnected as not needed, two pumps on throttle put enough fuel through for starting, couple of blips to get the engine initially warm and away you go, far better economy and the extra power when needed.
Most auto chokes ended up sticking or going out of adjustment, though i seem to recall Nikki carbs having an adjustable choke which could be fine tuned as the vehicle aged, these in typical Japanese reliability were usually trouble free.
I always preferred manual chokes on my carbed cars, complete with standard clothes peg/handbag depending on your persuation accessory when the pull/twist lock function failed to grip.
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I didn't mind some of the more ordinary auto-chokes of the 80s as fitted to Ford and Citroen for example. They often needed a tweek by the time they'd done a few years and the problem was usually few folks (including garages) read/understood the manual or took the trouble to set them up by the book.
The real headaches came with the very complex versions fitted to VW/Audi with various electrical and vacuum devices plus a hedgehog in the manifold. They would really try your patience.
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S'funny how Jap cars with auto chokes rarely if ever gave troubs.
Auto choke probs kept me in work for 14 years, especially the Ford VV, GM Varajet,
not forgetting the Skinners Union ~ en.wikipedia.org/wiki/SU_carburetor
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My Carina has one - doesnt seem to work very well mind you!
According to the book, depress the throttle once, then start the car with no throttle, run for ten seconds, blip the throttle again and drive away.
In practice, turn the key, once the starter motor kicks in, half throttle, hold that for 20 seconds, then drive away.
I think the choke element of the carb sticks a bit and it doesnt actually deliver the extra fuel. Ho-hum, old cars :-)
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I could probably still strip down, rebuild and set up a GM Varajet II carb with auto choke even now - I had to do so on my 1983 Cavalier many times over the two years I had it. I eventually bought a manual choke conversion kit - at one time these were so popular they were routinely stocked in petrol stations!
And Humph, yes I've had a few motors where a clothes peg has formed part of the minor controls...
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Jaguar XJ engines had an auxiliary carburettor to act as an auto choke in the 1970s. It was a poc. Tended to fail. I replaced mine for £80 which in 1984 was loadsofmoney.
I found Ford autochokes reliable.. but then they were newish cars..(company)...
Th best form of manual choke is mounted on the steering wheel... see my 1929 Riley -oops that was a hand throttle - as opposed to the advance/retard ignition...
Rover P4s iirc had a lovely choke which was well engineered and required no clothes peg...
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My Beetle would start reliably from cold with one press of the throttle to set the choke. Hot starting was a different matter however.
My Citroen Visa GT had huge twin Weber 35 carbs that you could have sent ferrets down. Starting on that auto choke was also faultless although ISTR you could get a kit to improve the Weber's operation. Never needed it or already fitted; I've no idea. The Haynes manuals of the day referred to the choke as a "strangler".
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>> The Haynes manuals of the day referred to the choke as a "strangler".
Which is a more correct term, I believe. I think the word 'choke' actually refers to the narrowed 'venturi' section of the carburettor - which produces the lowering of pressure required to 'draw' fuel in.
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I've always taken the word "choke" originally to mean the temporary restricting of air flow in order to force a richer mixture necessary when starting and initial running when cold.
I didn't realise "strangler" was the more accurate word, simply a variant.
Primitive chokes indeed just had a flap that partly closed off the air intake. I've also had a lawnmower where one was advised to hold one's hand over the air intake when cold starting, for a similar effect.
Later chokes often worked on a different principle, having a small bolt-on starter carburettor which was switched in when starting, and gave a much richer, often progressive, mixture.
I've had a Zenith-Stromberg where the choke worked by lowering the jet bridge, so that the same piston/needle position gave a richer mixture.
I remember Ford carburettors , eg the "Fomoco" fitted on my Saab 96, often had conversion kits available to convert the unreliable auto-chokes into normal manual operation.
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I had a Suzuki 125cc motorbike which had a simple manual choke.
It was in the form of a simple lever atop the carburettor.
The lever was spring-loaded and relied on friction to keep the choke 'on'.
(Bear with me, I'm getting to the point.)
One day, the lever came slightly undone, meaning the choke would not stay 'on' unless you held the lever down with your finger.
Trouble was, the bike only had a kickstart.
Ever tried kickstarting a bike with one hand under the fuel tank and the other trying to operate the throttle?
Not easy.
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>> I didn't realise "strangler" was the more accurate word, simply a variant.<<
Probably an American~ism.
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>> Probably an American~ism.
Of Boston origin?
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My first car (Fiat 127) had an auto choke that worked on a coil spring.
This expanded / contracted with the water feed from the engine.
Good idea in principle, only there was no way of manually turning it on or off.
When I first got the car it had intermittent starting problems and some times stalling when hot.
It turned out the flap mechanics were not connected to the coil spring so the choke was free to flap around when ever.
With this fixed the car was completely different.
Slightly odd in that idle was high for some time (when cars with other types of choke would have turned off by then) until quite warm.
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>>Good idea in principle, only there was no way of manually turning it on or off.
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I'm no expert in this field diddy, but could that be why it was called an auto-choke.
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you are correct, however I was trying (and failing) to point out that most 'auto chokes' can be turned off by blipping the accelerator.
not so in the case above.
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>> I was trying (and failing) to point out that most 'auto chokes' can be turned off by blipping the accelerator<<.
It makes one wonder why the blimming things ever came about in the first place,
take my Honda lawn mower ~ full choke to start (manual) and then pull back to the running position,
simples!
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>>It makes one wonder why the blimming things ever came about in the first place,
It's one of those things engineers strive to get rid of, and the logic runs along the lines of;
"give the user something to adjust or control, and they'll likely make a mess of it"
How many people used to try to start the car from cold without choke - or realise it was still out 20 miles into a journey?
there are lots of engineering rules of thumb in this vein - as an example
"design something that's capable of being wrongly assembled, and someone will assemble it incorrectly" - this leads to most of the things I design being assymmetric, and people have sometimes commented that my designs look odd - however, you can't put them together wrong!
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"design something that's capable of being wrongly assembled, and someone will assemble it incorrectly" -
It's amazing the number of times I have "fixed" friends USB devices by pulling them from the ethernet socket and plugging them into a USB socket, and I have seen a few VGA monitor leads destroyed by people trying to force them into a 9 pin serial port.
Here I must admit to damaging a torx bolt by trying to use an allen key when I couldn't see what I was doing.
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>> My Beetle would start reliably from cold with one press of the throttle to set
>> the choke.
You're lucky - I had to open the bonnet, manually reset the choke screw on its cam and then start the car!
I supose it was automatic in that it automatically turned itself off.
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I would have much preferred a manual choke with my Carina, its a pain in the backside. Next time Im getting something with injection.
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my Mk1 Astra (1.3) had a " GM Varajet II" Manual Choke, and it was a pig of a thing to get right, and I had no worries about having my car being stolen as it was only me that could get the Choke just right otherwise it would not start.
a point proven when i took it to my mechanic, and he could not get the car in the garage, as it would not start, i showed him how to do it with "you have to do it like this otherwise its a no go"
If you got it right, it never gave a problem 1st thing on a cold morining, it was if starting during the day then it was troublesome, to much or little, and the car would not start and you ran the risk of it flooding.
Again you had to slowly push it in over a period of time, too early, and the car would clearly struggle, to late, and then a too rich micture was inevitble and the car would splutter to a halt.
looking back i would not return to having a manual choke under any circumstances however the "youngsters of today" do not know they are born with their fuel injection systems and a car that starts on the turn of the key. no thinking ahead what is the best start up procedure depending on the time of day and outside temprature etc...with the niggling thought at the back of your mind that it might not start.
Last edited by: Redviper on Mon 17 May 10 at 16:11
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My dad had an automatic choke on his 1963 Hillman Imp, from what I remember (despite my love for Rootes products in general) it was the only part which worked reliably and had not started to rust within 18 months.
My Commer still has a manual choke which works fine, if you know what to do with it!
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>> "Youngsters of today" do not know they are born with their fuel injection systems and a car that starts on the turn of the key. No thinking ahead what is the best start up procedure depending on the time of day and outside temperature etc.
Nail, head. I reckon the removal of that interface goes a fair way towards explaining why so few drivers seem to have any mechanical sympathy any more.
Last edited by: Dave_TD {P} on Mon 17 May 10 at 18:05
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>> I would have much preferred a manual choke with my Carina, its a pain in
>> the backside. Next time Im getting something with injection.
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Not possible to put a cable in it's stead Stu and do away with the...(bimetal spring istr)?
OK a bit of fishing line then..;)
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As per an earlier post, I have a Honda mower with a manual choke. Full choke when cold and it starts first pull, even after having been unused all winter. You can turn the choke off after about 15 seconds, unless there's a chill in the air
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>> I would have much preferred a manual choke with my Carina, its a pain in
>> the backside. Next time Im getting something with injection.
>>
You're not changing the new car ALREADY are you?
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No choke was one of the attractions to buyers of early diesel cars.
The engines might have been slow and smelly, but at least they revved cleanly from the off.
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>> at least they revved cleanly from the off
If the new-to-diesel motorist remembered to wait 20 seconds for the glowplug light to go out!
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Knowing how to start your car depending on how cold the drivers seat felt, seperated male from female drivers.
It s a male only thing to be able to hear and feel one cylinder catching, and to tweak the throttle and choke to coax the others into life.
Last edited by: Zero on Mon 17 May 10 at 19:34
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TBH, auto chokes *usually* work ok when they're set up correctly,
If they've got the gimp, its often a punctured pull down diaphragm which will cause over choke conditions or a fairly simple to rectify fault with the bi-metal, VV's are a tad different of course.
Thorough cleaning of the gubbins with STP carb cleaner can work wonders as well.
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>>No choke was one of the attractions to buyers of early diesel cars.
As a lad I remember being the one to hold out the rich knob on the front grill of the truck. I was told it was put there to stop drivers pulling it out to overfuel the engine in normal running. Many just stuck a clothes peg behind it.
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My Old Man used the manual choke to pass his driving test in the late-50s. He left it out so that the engine idled a bit more quickly and was less inclined to stall when pulling away from stationary...
The there's the tale of the old biddy down the street who always pulled the choke out to the max so that she could hang her handbag on it....
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Early 'automatic' chokes - Zero
