FORD VAN POINTERS.
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By R. T. Nicholson (Author of "The Book of the Ford ").
4 6 AN I DECARBONIZE my own engine r
Certainly;you can. I know that it is usual to put the work out, the idea being that it is a slaed job, and that the average driver cannot tackle it He can—and should—save money. • •
72.—Decarhoniiing.
One thing is certain—that if the work is put out it will not be done nearly as often as it should be. Truth to tell, the Ford engine carboniies rather readily—more readily than most motor engines—and the work heeds to be clone pretty often if the carbon knock is to be avoided—and it is. The Ford engine carbonizes rather readily, mainly. because of the "rough and ready "—though efficient----systern of lubrication. That system is a splash system, without any complications in the way of pump or, filter : there is not even a hand pump to provide occasional additions to the working supply. Enough oil has therefore to be fed in through the breather pipe to last the engine for a given run. If there is enough in-the gankcase to serve at the end of the run, it stands to reason that there will have been too much there at the:beginning of the run—since some will have been used up in the course of the run. So, for mosttof the time, the, Ford 'engine is running on excessive oil. This excess works up into the combustion chamber, and on to the tops of the pistons themselves. There it is burnt, and forms carbon. Most of the carbon in any engine is just burnt, lubricating oil It is, however, also partly formed of burnt petrol—but not to any extent unless the ,grade of petrol is poor (which it mostly is at present), or unless the Mixture used is too rich. A mixture that is "just right" explodes properly, and leaves very little soot, or carbon, which is the same thing.
• " Precautions.
In view of what I have said, do not over-lubricate your engine ; use as good petrol as you can get (though there is precious little choice just now I), and look to your adjusting disc, so that the engine may run on a.s little petrol. and as much air, as she will take. I have in previous Pointers, dealt with these matters.
How Often ?
-I cannot tell you how often your engine should 'be. decarbonized. Much depends on your driving and your attention to the oil and petrol supply, upon the gradients of your roads, upon the number of starts and stops. But I can tell you when decarbonizing is needed. It is needed whenever your engine shows a tendency to knock in picking up speed under load, or . when pulling up t a long steep hill. If you have been driving a particular van for any length of time, you will.be able to tell easily enough whether the engine needs decarbonizing. Sooner or later, it will begin to knock in picking up after a cornert in starting tfrom slow to high speed, in tackling hills which the van once got up without effort. That means too much carbon.
Why the Knocking?
There has been a good deal of pow-wow among the experts as to why 'excess carbon causes knocking. A good enough explanation is this : As the carbon forms, it lessens the space in the eombustion chamber and gives higher compression. 'This means that the explosion becomes much more sudden than it was when the combustion chamber was comparatively clean. This nces,ns that the piston Fats no time to get out of the way when the explosion occurs. This means a banging Of the piston, instead of (relatively speaking) a push. The slower the engine is running, i
the less s the piston able to get out of the way : therefore. the more readily the engine knocks at slow speeds, when the resistance of the engine to the bang is at its greatest. All this means that the knocking is due te toe high compression in the combustion chamber.
Preparations for Decarbonizing.
Empty the water out of the radiator. It is not necessary to empty it all opt: a.gallon or a little more is enough. If I want to change all the water in the radiator, I empty the supply 'by means of the radiator petcock. (In-that case, it is usually necessary to poke a piece of wire up to start the flow, owing to filth collecting in the tap.) If I do not want to change all the water in the radiator, I slightly loosen the two bolts that hold the long outlet connection pipe to side of the cylinder casting. It is not necessary to slack these right nit: if loosened slightly, the water will flow out.of the water system till the level is as low as that of the bottom of the outlet. Next remove the four sparking plug cables from the sparking plugs, and tie them (the cables) together, and loop them up sut of the way. It is -best then to remove the sparking plugs themselves, so as to give them a good cleaning. Have a box ready to receive all the parts that you remove, so that you may not have to • play hide and seek for them latera good big box, say, 2 ft. sq.—and a sturdy one that will not tumble to pieces as you load it. • Better lay the plugs, however, in a bath of paraffin, to soak while you are doing ‘the work. '(It is a good thing to wash all _parts in said paraffin bath as you remove them, and before placing them in the box.)
Screw out the two bolts holding the cylinder head outlet connection (connecting up with the shortwater pipe near top of cylinder casting and-radiator). Sometimes it is difficult to budge these, and a hefty fixed spanner is required. The kit. fixed spanner—the one that you wilt later on use for removal of the cylinder head bolts—will fit and do the trick. Put it well over the bolt head, and apply steady force, without jerk-, ing. Lay bolts in box.
Now comes the big business. You have to remove the. 15 bolts on top of the cylinder head. For this job, you must positively have a fixed spanner of long leverage. For some years past, the proper tool has been included in the kit, but formerly was not. If you had it, and have lost.it, you must get a similar tool • for no adjustable spanner will serve, and no slighl fixed spanner will be of any use. And, in using the proper tool, work with care. Place the spanner socket well dyer each bolt head, and see that it stops there as you turn the bolt. Take good care that your hand does not fly off, owing to the tool slipping, for there are a lot of ugly sharp edges waiting about to catch and gash you. The right way to remove the belts is to loosen each for about one turn, and then to spin the bolts out with a box spanner that engages the bolt beads when held vertically, They will then come out "like winking." Otherwise, it is weary work turning out 15 bolts with a horizontal spanner.
The back bolts are best removed by working from behind the dash—the others by working from in front of it. •
Now you can remove the cylinder head. To do so, shove it backwards for j in. or so, and then lift it straight up and away, taking good care* not to drop it. Set it carefully somewhere, upside down, out of the way, so that you will not stub your toe on it.
Under the cylinder head you will find the cylinder gasket. This is a big metal-asbestos washer, which is there to make a gastight joint between cylinder casting and cylinder head. Treat it kindly, therefore, for it is not built to stand rough handling, when out of working position. Do not strain or tear it.Put it well out of the way by itself, on a shelf, flat. There is a second (small) gasket which you will find at the same time—the one between the cylinder head and the outlet connection—the bolts of which you previously removed -escue it, and set it with the bigger one on the shelf.
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Removing the Carbon.
The piston tops will now he exposed. You will find them coated with carbon. Your job is to remove that carbon. It is most easily removed from any particular piston head if you bring each piston up to its highest possible position by turning thestarting handle.
Before attacking the carbon, it is best to plug all the holes from winch you have removed the cylinder bolts—also the holes through which the water circulates. The water holes are best plugged with rag chunks. The bolt holes can be stopped with wooden' meat skewers, cut down to a suitable length, and of such thickness as to. fit the holes really snugly. The object of this plugging is to prevent carbon chips from getting into the holes.
The best tool for removal of the carbon is a cold chisel or a wide screwdiiver. Be careful not to scratch any metal in removing the carbon. The carbon will chip off, aid fly as you apply the biol. Do not hammer en the tool, Or you may smash a piston : simply scrape, without scratching. Finishing touches in corners can be made with a blunt strong pocket knife.
Let the removal of the carbon be really thorough. Wherever carbon is, there carbon' should net be. The valve heads should be cleaned ; and if, when you lift the valves in turn by slowly moving the starting handle you see any carbon under them, that shoultl be attacked,too. (Try, by the way, to prevent any carbon chips, as you scrape, flying under the valves that may happen to be lifted at that particular moment: they may ingke it hard for you to start her later on.) Now get the cylinder head, and lay it in an upside down position, on a good solid eupport.. Then serape from it every bit of carbon that you can find. Mind : do not scratch.
Blow or brush away from cylinder head and cylinder casting any chips of carbon that may be lying about. They will never be wanted again, and will do mischief if left, particularly on the flat of the cylinder head or that of the cylinder casting. if any carbon finds its way into, the holes—as it should'net do—you will have to get it out in the best way you can, otherwise there will be trouble. If it lodges in the water holes, and finds its way into the radiator, it may cause a partial block there. If it lodges in the bolt holes, it will prevent your getting the bolts home. The time for the removal of the carbon chips from the holes is before you replace the cylinder head, or you will have to take it off again later, if, for instance, you cannot insert a bolt because of a big stray chunk of carbon. That will make you angry. , Carbon chips can be blown out with a cycle pump, or fished out with a stick daubed with vaseline, or floated out on oil. Anyway, get the carbon out.
In my next contribution I will deal with reassembling.