10 hours ago, TheVat said:

Excellent (and nicely low tech) feature. Now to check today's tariff report to see if the UK can affordably send one over... 😃

I have a long time friend whose dad had a couple of small shops repairing and selling domestic electric goods like these. He told me back in the 90's that these rarely came compared to other makes. They would suck up a brick if the pipe was wide enough. They have a good spares system as well.

1 hour ago, exchemist said:

I am somewhat intrigued by the bit about the spark being advanced. I seem to recall the spark advance was controlled pneumatically on my old Morris Minor (1961 model) by a diaphragm in the distributor, connected to the low pressure in the inlet manifold. But I have a faint memory of being in an ancient vehicle, perhaps a school bus, in which there was a control on the dashboard with "advance" and "retard" on it, presumably so the driver could alter the ignition timing manually. Seems rather extraordinary. Was this common in the early motoring era and why was it done? I wonder if it was before fuel ignition quality (knock rating) was standardised.

It's my understanding that it is due to the dependency mismatch between the time it takes an engine to do anything, which is inversely proportional to the engine speed, and the constant time of deflagration of the fuel-air mixture in the combustion chamber.

Edited Saturday at 10:38 AM2 days by KJW

34 minutes ago, KJW said:

It's my understanding that it is due to the dependency mismatch between the time it takes an engine to do anything, which is inversely proportional to the engine speed, and the constant time of deflagration of the fuel-air mixture in the combustion chamber.

That is why one needs the ignition timing to vary with engine speed and load but my question was not that. It was about why it was apparently controlled manually on early vehicles and what would be the circumstances under which the driver would adjust it.

2 hours ago, exchemist said:

I am somewhat intrigued by the bit about the spark being advanced. I seem to recall the spark advance was controlled pneumatically on my old Morris Minor (1961 model) by a diaphragm in the distributor, connected to the low pressure in the inlet manifold. But I have a faint memory of being in an ancient vehicle, perhaps a school bus, in which there was a control on the dashboard with "advance" and "retard" on it, presumably so the driver could alter the ignition timing manually. Seems rather extraordinary. Was this common in the early motoring era and why was it done? I wonder if it was before fuel ignition quality (knock rating) was standardised.

One purpose of the advance retard mechanism was to prevent engine knock or pinking.

This was to do with fuel quality and load rather than engine speed per se.

(Particularly) Pre-war vehicles had fewer automatic adjustments for example manual choke.

Lorries and buses etc obviously had larger loads in the first place so were in greater need of manual adjustments.

This included advance-retard controls.

3 minutes ago, studiot said:

One purpose of the advance retard mechanism was to prevent engine knock or pinking.

This was to do with fuel quality and load rather than engine speed per se.

(Particularly) Pre-war vehicles had fewer automatic adjustments for example manual choke.

Lorries and buses etc obviously had larger loads in the first place so were in greater need of manual adjustments.

This included advance-retard controls.

Ah so it was indeed to do with variability in octane rating of the fuel. But would this have been in place of the kind of automatic adjustment of ignition timing I described on my Morris Minor, or just a supplementary control, to extend the range of adjustment to cope with fuel variation?

I have now looked up the history and found the concept of "octane rating" appeared towards the end of the 1920s. It looks as if the run up to WW2 led to development of high octane aviation fuel. Shell apparently pioneered "100 octane" aviation fuel, which became adopted as standard in the high compression ratio turbocharged aviation engines of the time. However there was no real standardising of octane ratings in road-going motor fuel until the 1950s. So maybe this accounts for the need to alter the timing manually, depending on the quality of fuel available.

17 minutes ago, exchemist said:

Ah so it was indeed to do with variability in octane rating of the fuel. But would this have been in place of the kind of automatic adjustment of ignition timing I described on my Morris Minor, or just a supplementary control, to extend the range of adjustment to cope with fuel variation?

I have now looked up the history and found the concept of "octane rating" appeared towards the end of the 1920s. It looks as if the run up to WW2 led to development of high octane aviation fuel. Shell apparently pioneered "100 octane" aviation fuel, which became adopted as standard in the high compression ratio turbocharged aviation engines of the time. However there was no real standardising of octane ratings in road-going motor fuel until the 1950s. So maybe this accounts for the need to alter the timing manually, depending on the quality of fuel available.

Octane rating was only one aspect of it.

Magnetos were used before the coil and distributor came along. ( and still are on aero engines for redundancy purposes )

Correct combustion depends upon temperature, mixture, timing compression ratios and as I already mentioned engine load.

Here is a better discussion than I can quickly construct.

full but easy to read explanation of effects of ignition...

Nice piece to read when you have time Timing explained in the easy way!

The most important concept to understand is that lean mixtures, such as at idle and steady highway cruise, take longer to burn than rich mixtures; idle in particular, as idle mixture is affected by exhaust gas dilution. This requires that lean mixtures have "the fire lit" earlier in the compression cycle (spark timing advanced), allowing more burn time so that peak cylinder pressure is reached just after TDC for peak efficiency and reduced exhaust gas temperature (wasted combustion energy). Rich mixtures, on the other hand, burn faster than lean mixtures, so they need to have "the fire lit" later in the compression cycle (spark timing retarded slightly) so maximum cylinder pressure is still achieved at the same point after TDC as with the lean mixture, for maximum efficiency.

The centrifugal advance system in a distributor advances spark timing purely as a function of engine rpm (irrespective of engine load or operating conditions), with the amount of advance and the rate at which it comes in determined by the weights and springs on top of the autocam mechanism. The amount of advance added by the distributor, combined with initial static timing, is "total timing" (i.e., the 34-36 degrees at high rpm that most SBC's like). Vacuum advance has absolutely nothing to do with total timing or performance, as when the throttle is opened, manifold vacuum drops essentially to zero, and the vacuum advance drops out entirely; it has no part in the "total timing" equation.

At idle, the engine needs additional spark advance in order to fire that lean, diluted mixture earlier in order to develop maximum cylinder pressure at the proper point, so the vacuum advance can (connected to manifold vacuum, not "ported" vacuum - more on that aberration later) is activated by the high manifold vacuum, and adds about 15 degrees of spark advance, on top of the initial static timing setting (i.e., if your static timing is at 10 degrees, at idle it's actually around 25 degrees with the vacuum advance connected). The same thing occurs at steady-state highway cruise; the mixture is lean, takes longer to burn, the load on the engine is low, the manifold vacuum is high, so the vacuum advance is again deployed, and if you had a timing light set up so you could see the balancer as you were going down the highway, you'd see about 50 degrees advance (10 degrees initial, 20-25 degrees from the centrifugal advance, and 15 degrees from the vacuum advance) at steady-state cruise (it only takes about 40 horsepower to cruise at 50mph).

When you accelerate, the mixture is instantly enriched (by the accelerator pump, power valve, etc.), burns faster, doesn't need the additional spark advance, and when the throttle plates open, manifold vacuum drops, and the vacuum advance can returns to zero, retarding the spark timing back to what is provided by the initial static timing plus the centrifugal advance provided by the distributor at that engine rpm; the vacuum advance doesn't come back into play until you back off the gas and manifold vacuum increases again as you return to steady-state cruise, when the mixture again becomes lean.

The key difference is that centrifugal advance (in the distributor autocam via weights and springs) is purely rpm-sensitive; nothing changes it except changes in rpm. Vacuum advance, on the other hand, responds to engine load and rapidly-changing operating conditions, providing the correct degree of spark advance at any point in time based on engine load, to deal with both lean and rich mixture conditions. By today's terms, this was a relatively crude mechanical system, but it did a good job of optimizing engine efficiency, throttle response, fuel economy, and idle cooling, with absolutely ZERO effect on wide-open throttle performance, as vacuum advance is inoperative under wide-open throttle conditions. In modern cars with computerized engine controllers, all those sensors and the controller change both mixture and spark timing 50 to 100 times per second, and we don't even HAVE a distributor any more - it's all electronic.

Now, to the widely-misunderstood manifold-vs.-ported vacuum aberration. After 30-40 years of controlling vacuum advance with full manifold vacuum, along came emissions requirements, years before catalytic converter technology had been developed, and all manner of crude band-aid systems were developed to try and reduce hydrocarbons and oxides of nitrogen in the exhaust stream. One of these band-aids was "ported spark", which moved the vacuum pickup orifice in the carburetor venturi from below the throttle plate (where it was exposed to full manifold vacuum at idle) to above the throttle plate, where it saw no manifold vacuum at all at idle. This meant the vacuum advance was inoperative at idle (retarding spark timing from its optimum value), and these applications also had VERY low initial static timing (usually 4 degrees or less, and some actually were set at 2 degrees AFTER TDC). This was done in order to increase exhaust gas temperature (due to "lighting the fire late" to improve the effectiveness of the "afterburning" of hydrocarbons by the air injected into the exhaust manifolds by the A.I.R. system; as a result, these engines ran like crap, and an enormous amount of wasted heat energy was transferred through the exhaust port walls into the coolant, causing them to run hot at idle - cylinder pressure fell off, engine temperatures went up, combustion efficiency went down the drain, and fuel economy went down with it.

If you look at the centrifugal advance calibrations for these "ported spark, late-timed" engines, you'll see that instead of having 20 degrees of advance, they had up to 34 degrees of advance in the distributor, in order to get back to the 34-36 degrees "total timing" at high rpm wide-open throttle to get some of the performance back. The vacuum advance still worked at steady-state highway cruise (lean mixture = low emissions), but it was inoperative at idle, which caused all manner of problems - "ported vacuum" was strictly an early, pre-converter crude emissions strategy, and nothing more

1 hour ago, studiot said:

Octane rating was only one aspect of it.

Magnetos were used before the coil and distributor came along. ( and still are on aero engines for redundancy purposes )

Correct combustion depends upon temperature, mixture, timing compression ratios and as I already mentioned engine load.

Here is a better discussion than I can quickly construct.

full but easy to read explanation of effects of ignition...

Nice piece to read when you have time Timing explained in the easy way!

Yes but again nothing about how a driver would use the manual adjustment on old cars. Nice MGB GT, though.

I had a teal blue roadster in the early 80s. XDL152L. I looked up the reg on DVLC a couple of years ago - and she’s still going! I sold her when I went off to Dubai in 1983.

Edited Saturday at 01:36 PM2 days by exchemist

39 minutes ago, exchemist said:

Yes but again nothing about how a driver would use the manual adjustment on old cars. Nice MGB GT, though.

I think the explanation you are looking for can be found in this thread:

https://www.honestjohn.co.uk/forum/post/index.htm?t=101567

In those days cars had a lever, normally mounted on the centre of the steering wheel, that allowed the driver to manually adjust the ignition timing, in this case moving the lever up advanced the ignition "raising the spark", whilst moving the lever down "lowering the spark", retarded it.

If you started the car by hand, you would retard the spark timing to after TDC, otherwise there would be insufficient momentum in the crank to get past TDC. If the engine fired, the piston could be pushed back down the way the bore -  ie backwards. The starting handle would then whip out of your hand, spin round and whack your arm on the other side!

The engine would (hopefully) idle albeit roughly until you could move round to the cabin to advance the timing.There wasn't any vacuum advance or centrifical mechanical advance on the early cars. It was all done by ear. Cranking a car was a hazardous occupation!

The internal timing of a magneto ignition system on these early cars was controlled  by a linkage that adjusted an internal cam ring  with a bump which knocked the points open creating a spark.

https://www.themagnetoguys.co.uk/magneto-internal-timing

The strength of the spark depended on the spacing between the bump point and  the flux points of the permanent magnets in the armature

49 minutes ago, toucana said:

I think the explanation you are looking for can be found in this thread:

https://www.honestjohn.co.uk/forum/post/index.htm?t=101567

The internal timing of a magneto ignition system on these early cars was controlled  by a linkage that adjusted an internal cam ring  with a bump which knocked the points open creating a spark.

https://www.themagnetoguys.co.uk/magneto-internal-timing

The strength of the spark depended on the spacing between the bump point and  the flux points of the permanent magnets in the armature

Ah yes, that’s it. So originally all the timing adjustment was manual, without any automatic centrifugal or inlet manifold compensation. So the driver tuned it by ear, presumably optimal just before the onset of pinking.

And sure, if you did not fully retard the spark when cranking, the engine could fire backwards, in which direction the ratchet would not disengage, so the handle would whizz round, potentially breaking your arm.

But I can’t help thinking there may have been an intermediate point, later on, when automatic compensation had come in but there was still a need to adjust for variations in octane number of the fuel.

8 hours ago, toucana said:

Wrist and arm fractures caused by cranking over early automobile engines with the starting handle were once so common that doctors coined a new medical term for it -  ‘Chauffeur’s Fracture’.

They were called Ford Fractures here. America was still largely rural then and most would not have cared for "chauffeur." My grandparents also spoke of "gaslight branding" in evening drives, where you lit the headlamps, and then if you absentmindedly rested your left hand on a headlamp while bracing to crank, the raised company logo could be burned onto your palm.

My memory only goes as far back as points with vacuum/centrifugal advance in the distributor, and changing spark plugs every so often.

23 minutes ago, TheVat said:

grandparents also spoke of "gaslight branding"

To this day, you can still seriously burn your fingers when 'handling' hi-intensity Halogen bulbs in car headlights.
( you should also avoid 'handling' as the oils on your fingers contribute to early bulb failure )

Thank goodness for hi-power LED bulbs, distributed coils, and electronic fuel injection/engine management systems.
( although I would love an old MGB, TR4/6, Alfa Romeo Spyder, or, of course, a Jaguar XKE even with the fiddly v-12 engine )

1 hour ago, TheVat said:

They were called Ford Fractures here. America was still largely rural then and most would not have cared for "chauffeur." My grandparents also spoke of "gaslight branding" in evening drives, where you lit the headlamps, and then if you absentmindedly rested your left hand on a headlamp while bracing to crank, the raised company logo could be burned onto your palm.

I remember my grandad, sometime in the 60's, cranking the engine of his Morris Minor one day.

hi Folks, you really do make me aware of my age

One of the first motorbikes I had was a Panther 350 with an ignition timer control on the handle bars. It could give you a nasty kickback if you set it too far advanced when kick starting. On the other hand you could Get a gentle response that I'd describe as soft and soggy when travelling on icy roads. One of the first 4 wheeled vehicles I had was a Ford Thames van with a starting handle. The advice was don't wrap your thumb around the handle so that if it kicked back on starting it could jump out of your hand without hurting too much.

BTW That was the early 1960's when I met a girl who happily rode pillion, seemed to get less keen when we got engaged and exerted all her influence on me to acquire 4 wheels once we were married. :)

5 hours ago, StringJunky said:

I remember my grandad, sometime in the 60's, cranking the engine of his Morris Minor one day.

Do you mean by hand? I thought the Minors had electric starters from their beginning in the twenties. (Or was there an optional crank attachment for low battery situations?) Don't think I've seen anything besides a Model T be hand-cranked, and that was done as a feat of daring at an antique auto show. I remember them saying "don't wrap your thumb around," as @OldTony mentioned above.

This chat takes me back to my earliest automotive memories when our family had a 1958 Renault Dauphine. The 845 cc engine produced a dizzying 0-60 in 30 seconds, and you had to use a tire pressure differential in order to prevent oversteer. I think my Dad grew disenchanted with the steering issue and had traded it in by the time I reached kindergarten. But it was cute as a button.

Family joke from this era: I like the Renault, but I Constantinople.

(sorry)

2 hours ago, TheVat said:

o you mean by hand? I thought the Minors had electric starters from their beginning in the twenties. (Or was there an optional crank attachment for low battery situations?) Don't think I've seen anything besides a Model T be hand-cranked,

We had an Austin A40 and I think it had a crank handle that may or may not have seen action .

We then had an Austin A50(A55?) and I don't remember if it also had that accessory.

Edited Sunday at 03:28 AM1 day by geordief

49 minutes ago, geordief said:

We had an Austin A40 and I think it had a crank handle that may or may not have seen action .

We then had an Austin A50(A55?) and I don't remember if it also had that accessory.

The A40 had the same A-series engine as the Minor. My Minor was 948cc though there was a 1098cc version and even, in some later Minis, a 1275cc version. But quite small engines and I suppose feasible to crank by hand. I think there was a free end of the crankshaft at the front to which a crank handle could be fitted, as your picture of the A40 shows. But I didn’t have a crank handle for it and would never have dared to try that. If the battery went flat one would get some mates to give it a push, just as my son now does with his Fiat Panda, or use jump leads.

6 hours ago, TheVat said:

Do you mean by hand? I thought the Minors had electric starters from their beginning in the twenties. (Or was there an optional crank attachment for low battery situations?) Don't think I've seen anything besides a Model T be hand-cranked, and that was done as a feat of daring at an antique auto show. I remember them saying "don't wrap your thumb around," as @OldTony mentioned above.

This chat takes me back to my earliest automotive memories when our family had a 1958 Renault Dauphine. The 845 cc engine produced a dizzying 0-60 in 30 seconds, and you had to use a tire pressure differential in order to prevent oversteer. I think my Dad grew disenchanted with the steering issue and had traded it in by the time I reached kindergarten. But it was cute as a button.

Family joke from this era: I like the Renault, but I Constantinople.

(sorry)

Pe-1971 had hand cranks. My grandad was an airframe and engine fitter/mechanic, so he would have likely been knowledgeable to the means of turning engines over safely.

I had two Morris Minors in the early 1970s. My brother had an A40 Farina.
A traveller and then a saloon, both ancient 2nd, 3rd, 4th.... hand by the time I got them, but they were so easy to work on.
I bought the works manual from BMC and was tickled by the chapter on Africa. (The motors were designed for british southern and east Africa).
There was a whole chapter on how to find a blacksmith if you broke down in the Veld, and how to make a boy scout tripod to lift an engine out.
In the 1973 fuel crisis I managed to keep the last one going by fitting a modified Ray Martston electronic ignition, I originally built for a ban-the-bomb Cortina, and mixing some diesel with the petrol.
The engine didn't like it and the car ran slowly, but it did get me to work and back evey day at Heathrow.

6 hours ago, StringJunky said:

Pe-1971 had hand cranks. My grandad was an airframe and engine fitter/mechanic, so he would have likely been knowledgeable to the means of turning engines over safely.

Makes sense, I guess, to go ahead and put in gearing for a hand crank, as a backup. What I am grappling with is that you Brits seem to have named an Austin after breakfast porridge. Perhaps it is just as well we may be withdrawing from NATO. 😎

4 hours ago, studiot said:

In the 1973 fuel crisis I managed to keep the last one going by fitting a modified Ray Martston electronic ignition, I originally built for a ban-the-bomb Cortina, and mixing some diesel with the petrol.

Several things here I don't grasp. What is a ban-the-bomb Cortina? And how could one put diesel mix in a gas engine and not ruin it? Does the right blend help if there's a weak spark?

I am happy to report I figured out a saloon model is what we call a sedan, so I'm now understanding the style isn't quite as fun as it initially landed on American ears.

10 hours ago, geordief said:

We then had an Austin A50(A55?) and I don't remember if it also had that accessory.

What really capped that video nicely were the end credits - the cranking man is Fat Bloke, played by George Clooney.

4 hours ago, TheVat said:

Several things here I don't grasp. What is a ban-the-bomb Cortina?

It's a reference to a distinctive type of tail light found on a number of British automobiles of that period. It bears a resemblance to the three-pointed symbol of CND (Campaign for Nuclear Disarmament) aka the "Ban-the-Bomb" protest movement of the late 50s and early 60s in UK.

26 minutes ago, toucana said:

It's a reference to a distinctive type of tail light found on a number of British automobiles of that period. It bears a resemblance to the three-pointed symbol of CND (Campaign for Nuclear Disarmament) aka the "Ban-the-Bomb" protest movement of the late 50s and early 60s in UK.

Didn't some Mercedes of the era have similar?

18 hours ago, exchemist said:

The A40 had the same A-series engine as the Minor. My Minor was 948cc though there was a 1098cc version and even, in some later Minis, a 1275cc version. But quite small engines and I suppose feasible to crank by hand.

Worth noting that from WWII to the early '50s the British public didn't have access to anything above 70 octane. Consequently production vehicles were built with low compression ratios. Hence the first family car I remember (1960-61ish) a hand cranked A30, would have had a compression ratio of about 7:1.

5 hours ago, toucana said:

It's a reference to a distinctive type of tail light found on a number of British automobiles of that period. It bears a resemblance to the three-pointed symbol of CND (Campaign for Nuclear Disarmament) aka the "Ban-the-Bomb" protest movement of the late 50s and early 60s in UK.

Ah yes, the symbol designed for CND (based on semaphore flag code), which spread to other countries eventually as the peace symbol.

Mercedes was similar. I remember my org chem professor drawing its three point star mounted on a benzene ring, creating the visual pun Mercedes Benzene.

53 minutes ago, sethoflagos said:

Worth noting that from WWII to the early '50s the British public didn't have access to anything above 70 octane. Consequently production vehicles were built with low compression ratios. Hence the first family car I remember (1960-61ish) a hand cranked A30, would have had a compression ratio of about 7:1.

70, yikes. That would knock like a stormtrooper at normal compression ratio, and I can picture it dieseling for minutes after shutting off. Heck, if the octane were much lower it would be halfway to being diesel. At least in the sense of little resistance to spontaneous combustion.

Wow.
The first vehicle I had access to when I turned 16 in 1975 was a 1973 Chevrolet Chevelle with a 350 ci ( 5.7 liter ) engine and 4 bbl carburation.
It had so much low end torque, that when I stomped the gas pedal, it would spin the bias-ply ( no radials ) tires, in a cloud of smoke, for about 200 ft.

Ahh, the good old days.
When gasoline was about $0.60 per gallon ( about $0.15 per liter )
Yes, I did my fair share of contributing to global warming ...