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FORD VAN POINTERS.

21st June 1921, Page 31
21st June 1921
Page 31
Page 32
Page 31, 21st June 1921 — FORD VAN POINTERS.
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Which of the following most accurately describes the problem?

By R. T. Nicholson (Author of "The Book of the Ford").

POPULAR mistakes die hard, and there are a, lot of them about—even in the motoring world, and even in the Ford world. Here is an effort to " nail " some of them.

358.—The Use of Petrol.

(1) No ; it is not petrol, or benzole, that explodes in the engine. Neither petrol nor benzole will

• explode : they simply burn. It is a mixture of petrol or benzole with air that explodes; and the mixture needs very little spirit in comparison with air.

The Value of Air.

(2) No; you do not get more power by increasing your spirit supply : generally you want more air, not more spirit. Very few carburetters admit as muchair as is needed by a warm engine : hence the value of au " extra-air " fitment. True, the Holley carbu,retter of the Ford gives you a means of cutting down your spirit supply (by reducing the spray orifice a.s the result of turning clockwise the carburetter adjust on the dash): true also that this gives you somewhat the same effect as admitting extra air ; but it gives you nothing like so fine, and so controllable, a mixture as an extra-air fitment will do.

That " Rich " Mixture.

(3) No; you do not want a " rich" mixture for your start from cold : you want just the same mixture as at any other time—for example, when the engine is hot. You shut your air control on starting from cold, not because that will give you a " rich " mixture, but because, unless you did so, you would not get even a poor mixture. When you shut that air control, you do truly get a lot of liquid spirit slopped about in your induction pipe' and you must have a lot of spirit so slopped about because cold spirit vaporizes very badly. Unless, .therefore, there is plenty of it exposed to the air that still passes to the engine (notwithstanding your having shut the air control), you will not get your regular explosive mixture at all. That is why you flood y a, " rich" mixture, but for (or benzole) which will give mixture. '

The Wickedness of Valve Grinding.

(4) No; it is not good practice for you to be always grinding m your valves with the idea of getting good compression : because, if you are always at it, you willdo more in the way of grinding your valve Beatings out than in the way of grinding your valves in. In point of fact, I will never, never have my valves ground in : I have them trued up in a lathe, by a man who knows what he is doing, and I only very lightly grind them into place (with earborundum and

oil) when I put them back. (Of course I wash away

all trace of the grinding material.) course, keep my

compression good—so far as it depends on the valves —without gnawing into the good metal of my engine.

Do Shocks Hurt?

(6) No; it does not necessarily hurt to get an electric shock. A low-tension shock may tickle you and make you jump, but that is all. It is the high-tension shock that hurts—though no high-tension shock that you can get off the Ford will hurt enough to damage. Still, it is not pleasant to get a shock from the plugs, or from the terminal nuts that carry the cables to the plugs. Never touch them when the engine is running.

Low and High Tension Electricity.

(6) No; there is not, any difference in kind between low-tension and high-tension electricity : it is only a difference in degree. It is a question of the number of volts delivered. Off your low-tension magneto, you can get 14-16, or a few more volts according to the speed of the engine. Off your volts, (on the new model) you can get only six. Off your hightension eircult you can get well over a thousand : that is why a high-tension shock hurts. Really, it is better to speak of primary and secondary circuits than of low and high tension. What we really mean when we speak of high-tension electricity on the Ford is induced electricity—not the electricity produced. by magneto or battery, but that induced in the coil-units in the way I have described more than once in these Pointers.

Getting Rich Quick.

• (7) No; induction does not give you a way of making

"lot " of electricity out of very little. It is perfectly true that you get over a thousand volts at the plugs, and only a few (25 at most) from the magneto —still less from the battery. What you do get at the plugs is rapid discharge for very short periods of time: what you get from the magneto is steady discharge of current all the time. If you fire a small shot, weighing a fraction of an ounce, you can do a lot of local damage with it—more than you can with a heavy weight rolled ,along the ground. That is because the shot has a great deal of velocity, with little weight, whereas, in the other case, there is a lot of weight, but little velocity. That is exactly the case with the high and low tension electricity on the Ford. The sparking-plug spit-fires are like the shot. The magneto output is like the slow-rolling weight. You could melt copper with the magneto current properly used; but you could not make it give you a spark guaranteed to fire the charge in your engine; on the other hand, you could not guarantee your sparks at the plugs to melt copper, though they will fire the charge; because, to fire the charge, what is wanted is a, very spiteful spark, however short-lived it may be—which is precisely what you get. If you could make a, " rot" of electricity out of very little, you would have perpetual motion at once, and then you would make a fortune in just about five seconds, and would not have to drive a van any more all the rest of your life!

No Way.

(8) No: the magneto current does not get to the plugs at all : there is no way for it to do so. Its only purpose (as regards ignition) is to induce the hightension current in the coils. It does go to the horn, and (in the old model) to the headlights.

What the Ammeter Says.

(9) No; the ammeter does not tell you anything about the " strength" of the battery. Only a voltmeter or a hydrometer will do that. The ammeter tells, you only of the measures of electricity that are going to the battery from the generator, or from the battery for lighting (or to induce high-tension current in the coils, when the ignition switch is set to " Bat."). There are quite a lot of•drivers who suppose that the ammeter reading tells them what the state of their battery is. They might •just as well suppose that the rate at which a man ate his dinner showed how strong he was. As. a matter of fact, a man who was nearly starving would probably gobble food up very quickly, though heewould be very weak. The ammeter reading simply tells you of the rate at which the battery absorbs, or gives back, current.

Oil and Lush.

(10) No; once the engine is well run in, it does not work best when it is richly fed up with oil. In point of fact, it works best when it has just enough, and not too much, for immediate needs. Surplus. over and above that is simply there to save you the nuisance of hopping down all the time to feed in more oil.

_ The So-called Commutator.

(11) No; the " commutator " which times your sparks is not a commutator at all., A commutator is that part of the generator which transformsalternating electricity into continuous, or direct, electricity. There is no such action in your timer—and I should like to get hold of the man who, first called that part a "commutator," and tell him what I think about it. (He could not have thought about it at all 1) Do call it a " timer," please.

Plug-point Setting.

close setting of the sparking plug necessarily give you easy starting. There is a limit—not only because a. very narrow gap easily soots up, and so defeats your object, but also because, to get a good hot spark, you must have a fair gap. (With a very narrow gap, the electricity has so little to do in jumping it, that it does not get very hot In the ,attemps —and you want heat to fire your mixture.) The right gap is, in the case of the Ford, 1-32nd inch—wider than on engines fitted with highignition.

On Keeping Cool.

(13) No ; a cool engine does not run best: a hot *engine pulls far better than a cool one—always provided the water does not actually boil. You must keep the engine heat down to that extent, or your water will boil away, and then you will get far too much heat. The fact is -that the right temperature for the water is somewhere between 190 degrees and 200 degrees—which, is very little short of the 212 degrees of boiling water. In theory, an engine would run better and better the hotter it got.; but there are practical limits to this—set by the limit of the heat which the lubricating oil will stand. You nanst have the parts lubricated, to prevent their welding together ; and you,cannot getra serviceable oil which will continue to lubricate at a temperature much higher than 1u0-200 degrees. B34,

'Ware Metal Insertions.

(14) No; brake bands with metal insertion in the fibre are not best for the Ford : they are very bad for it. You sometimes hear it Said that the metal insertion gives life to the bands, and so saves the need of frequent replacement. It may-do this, but it has two very bad effects which more than outweigh the advantage of long life in the ;bands. First, the metal woven into the bands scores the drums, which the bands grip; secondly, it chips off, or breaks off, gets down into the oil, and is thence hung up to foul and short-circuit the magneto. And what is true of the brake band is also true of the other two bands. Never have any metal in them. (This by no means condenins,the use of such bands for other vans than the Ford ; for metal/insertion fibre is often " just the thing " for them.) '1heir Fig. 227.— Temperabrake bands and drums are not lure and power. enclosed.

Rare Of effiZiency with most Oils Heate„ efficiency

212

Boilirm6 PoiriT

Fire!

(15) No • petrol cannot be fired, with a. cigarette end, (at least, I am pretty sure it cannot, though I never tried). Nevertheless, do not smoke cigarettes when there is petrol about, because the practice gets you into careless ways at a time when you ought to be specially careful. Before you know what you are doing, you have thrown awarthat,cigarette end, and lighted up a new Woodbine (or something less classy), and then—" up goes the donkey "which may be youl Where there's smoking, there's often fire— when there is.petrol about.

Tags

Organisations: US Federal Reserve
People: R. T. Nicholson

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