• FORD VAN POINTERS.
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By R. T. Nicholson (Author of " The Book of the FOrd").
IN WINTER, I like the driving seat of the Ford. It is so warm and snug there, the Ford being, so to speak, fitted with " central heating." The welcome warmth creeps up through those slots in the footboards, and warms the feet, legs, and all the rest of you.
But in summer, that same "central heating " is apt to be somewhat oppressive. Those slots are then a bit of a nuisance. With the temperature at 90° in the shade, no driver asks for more of it.
101.—On Keeping Cool.
If you could only close these slots, you would be able to keep much cooler. Very well, you can ; and without in any way interfering with the free action of the pedals and the hand-brake lever. It is quite an easy job.
Remove the metal plates which surround the pedal slots and the hand-brake lever slot. (This simply means taking out the screws.) Out of an old rubber inner tube, cut strips of rubber that will reach along the full length, and across the full width, of each metal plate. You can use the metal plates themselves as guides in cutting round the rubber, or you can cut the rubber out roughly and trim it to shape after you have it in position later. Deal with the pedal slots first. Take one of the metal plates, put one of the rubber strips under it, and replace the plate in its original position With
the rubber strip below it. Use screws about:* in. longer than the original screws, so as to allow for
the additional thickness of the rubber. (By the way, it is best to pierce the rubber for the screw holes : and in turning the screws into the wood, do
not force too much, or you will split the wood—
which, being heat-dried, is rather brittle.) Then slit the rubber strip right down the middle along the whole slot opening with a sharp knife. Just slit cleanly, cutting none of the rubber away at the slit. (It is best to rule a line with an aniline pencil to guide you in cutting the slit.) This slit is, of course, meant to allow for the fore and aft movement of the pedal stem. You will now have a floorboard looking like that shown in Fig. 1.
Treat the hand-brake lever slot in the same way. In this case, however, you will have to slit the rubber (at all events enough to pass it over the lever) before you screw the metal plate on to the rubber.
You now have all the slots closed except just where the pedal stems or the hand-brake lever pass through. As the pedals or hand brake are moved; the slots close fore and aft of them. You thus keep back the current of hot air that tries to get through from the engine.
This is one of the few uses (other than sale as " scrap ") that I have ever been able to find for old inner tubes.
102.—What Not to Do.
You are sometimes recommended to coast down a steep hill with the clutch in (i.e., as in straightforward running), and with the ignition switched off. The idea is that you thus kill two birds with one stone : (1) You cool your engine, and (2) you use compression as a brake, inasmuch as the " mixtUre ' that is sucked into the engine cannot fire, with the spark cut off, and as the pistons compress it as usual, the resistance of the gas " holds the van back, So far, so good. You do kill those two birds ; but the worst of it is that you are very apt to kill yoUr silencer also when you switch on again. What happens, of course, is that, at the moment when you switch on, your exhaust-pipe .and silencer are full of unexploded mixture, and the first glowing exhaust that gets out of the combustion chamber fires it, and you have a really good "'bust up." Now the Ford silencer—like most other parts of the Ford—is strong enough to stand the strain which it was built to stand ; but it will not stand the strain of a good healthy internal explosion ; and the first thing you will hear is a machine-gun working in the neighbourhood of your back axle: and the next thing you will do will be to walk back to pick up your silencer shell--or what there is left of it—away back on the road. So, if you must cool and brake like that, see that you can keep your throttle closed down while you are coasting with your ignition switched off: then when you switch on again have your ignition well retarded. The result will be that you will only have a very weak mixture in your silencer,. and if any explosion does occur, it will only be a mild one that will not blow the thing to pieces.
There is one objection, however, to ooasting with a closed throttle (and with ignition off): A lot of oil is sucked up past the piston rings, and that oil will carbonize directly the engine begins to fire again, and carbon is a nuisance. You see why the oil gets there, do you not? So long as the throttle is open, the engine sucks in air and petrol-gas through the carburetter. Directly you shut your throttle, there is no way in for this air and gas, so that each piston on its, downward travel creates a more or less complete vacuum ; and, as we were told at school, "Nature abhors a vacuum," and the oil on the cylinder walls oozes up past the piston rings, settles on the tops of the pistons, and there you are—or rather, there the carbon is.
No; to use a compression brake with really good effect, you ought to make it an air-brake—not a vacuum brake ; and that means having an extra-air fitment., .about which I am now going to write.
103.—Air as Brake Power.
There's air: why not use it? The atmosphere. I believe, extends some 100 miles above the earth: it is free of Government tax : it is a fine motor fuel (with a little spirit mixed with it), and the necessary fitment that will enable you to use it costs but a few shillings.
I am going to deal first with the extra-air fitment used only as a brake. It is not mainly intended for that use, but I am going to deal with it first from that point of view. Every such fitment involves the drilling of the inlet manifold at a point between the throttle and , the engine. The drilling is hest done close to the throttle—but not close enough to interfere with the movement of the throttle valve. Unless you are a skilled mechanic, you will not be able to drill and tap this hole yourself; and if you are a skilled mechanic, you will not need any detailed instructions from me as to the work.
Into the hole in question will be fitted some kind of valve, which will enable you to. admit extra air into the engine—that is, air over and above that which is sucked through the carburetter in the ordinary way. This valve is usually controlled by a lever on the steering column—often by Bowden mechanism. (The Bowden people make _a complete contsaption specially for the Ford.) When you coast down hill, and you have this arrangement "on board," you close your throttle, and open your extra-air valve full wide, leaving your clutch in. You have now cut off your petrol supply, but the falling pistons now draw into the engine draughts of cool, clean air, which refresh her vastly. There is no longer a vacuum set up to suck the oil up past the piston rings. And there you are again!
104.—The Perfect Mixture.
But the extra-air fitment really was not invented for the purpose described in the last Pointer: it was designed to give you a perfect explosive mixture at all engine speeds—one that contakis just the right proportions of air and petrol, and so gives maximum explosiveness at lowest cost. Of course, you are told that modern carburetters are automatic—that they look after the mixture without your worrying about a little thing like that. But I am one of those sceptical people that do not believe in any carburetter being automatic: I readily agree that all modern carburetters do partly accommodate the mixture to the conditions of the moment—make the mixture somewhere about right —but I do not believe that any carburetter that ever was could do the thing just rightly every, time. Unless fitted with some means of keening the proportions ,of air and petrol right, "by hand," I con c50 tend that no carburetter ever did give perfect results all the time.
In practice it is a fact that the quicker the engine runs, and the hotter it gets, the more petrol, and (relatively) the less air' is tended to be sucked in. At high engine speeds, the air lags more than petrol.
On most motorcycles, hey provide for this by , giving the rider an air-lever on the handlebars. But not so on cars and vans. No, the car and van driver is supposed to be either too lordly, or too lazy, or both, to want to fiddle with an extra lever. So the poor engine has to run on a " near enough" mixture—on a mixture that is 'as strong as tea that has stood for an hour—once it gets warmed up and really moving. With the extra-air fitment you can get that mixture correct to a very fine point. At starting, and until the engine is warmed up, you keep your extraair valve closed. As it gets going, you will find it possible to open the valve farther and farther, till "popping back" in the carburetter begins; then you will know that you have overdone it, and should close the valve down a bit. You adjust till you have got matters "just right" giving the maximum of power with the minimum of petrol gas for the speed desired.
Mark the advantages : Saving of petrol, by substitution of air ; a cleaner engine ; a cooler engine ; an air-brake on hills ; a. better lubricated engine (because the hot, thin, _baked oil on the cylinder walls gets exchanged for clean, new oil whenever you coast down hill). These things are worth having. You "cannot be bdthered " with an extra lever. All right—you do not have to have it. I am only pointing out the advantages in saving of money, sweetness of running and convenience. But as regards extra trouble, let me just say that the control of the extra-air lever soon becomes entirely automatic—and that you do not have to think about it at all.
105.—Does the Engine Need Extra Air ?
I have said that all .carburetters are the better for the extra-air fitment—that is _so, but some carlauretters want it more than others. No two carburetters (even when of the same make) behave exactly alike. Here is a way in which you can tell whether your carburetter would be the better for the fitment.
Start up. Setthe dashboard-adjusting disc so that the engine will fire at its best. Drive the van for a mile or so : then see if you can turn that disc down a lot fAxthers–a quarter of a turn or so. If you can, your engine would be the better for the extra-air attachment: if you cannot turn down farther, or only a little farther, you. will not gain a great deal, so far as correctness of mixture is concerned, by fitting.
You see what this test shows you. If you can turn the adjusting-disc down, it means that the
engine is better for less petrol. More air is, in practice, the same thing as less petrol (or benzole), since it is all a question of 'proportions. If you would be constantly adjusting the disc, the effect would be pretty much the same as that of adjusting the extra-air lever, but you cannot always be adjusting the disc, and the extra-air adjustment is more accurate, and, in any event, the extra-air fitment gives you the air-brake, which is worth having. Just one cautions If you have the contraption fitted, see that it is well fitted, that if is tight when closed. Otherwise, when the winter comes again, you may have more than usual trouble in starting, owing to leakage of air through the valve, which will so •weaken the cold mixture that it will not fire.
Much that I have said in this set of Pointers will a,pnly to other vans than the Ford, though specially 'written with the Ford in view. I am an extra-air
advocate for every carburetter that is, was, or .shall be.