Motor-car principles; the gasoline automobile

In order that an automobile may be maintained at its highest efficiency, a constant watch must be kept over all of its parts, and repairs and replacements made as soon as the necessity is apparent. A worn bearing or loose part may continue to operate, but the wear will be far greater than would occur under normal conditions, and may result in serious breakage. A system of inspection to be gone through every time that the car is used will keep the driver informed as to its condition, and it is best to form the habit of doing this at the end of a run rather than before, for then the necessity for making readjustments or repairs will be fresh on the mind.

INSPECTION

The condition of the ignition circuit and of the compression will be shown in revolving the crank shaft twice, and the action of the carburetor may be ascertained at the same time. Pushing the car across the floor will show the presence of tight brakes or wheel bearings, and the tires may then be examined for cuts. Beginning at the front of the car, every bearing not fed by the lubricator should be oiled, and all grease cups given a slight turn, those that are empty or nearly so being filled. While this is being done, a watch may be kept for nuts and bolts that may have been loosened by the vibrations.

WASHING

The car should be washed with clear, cold water only, and mud floated off; to remove mud by rubbing or any other method than sluicing it away by the action of a gentle stream of water will scratch the varnish and ruin the appearance of the car. When clean, the varnished parts may be dried with chamois or wash leather, and the finish retained by a light coating of a good furniture polish, which is to be immediately dried by rubbing.

The tires may be cleaned by sponging, but water should not be allowed to settle in the bead. On cars having the gravity system of gasoline feed, the water should not be permitted to splash on the tank, for it will enter through the vent. Water should also be kept from the upholstery, for if it enters the folds and buttonholes it will cause rotting.

THE TIRES

Light and heat are the worst enemies of rubber; spare tires should be kept in a cool, dark place, and protected from dust and moisture. French chalk, or some similar preparation, should be well dusted over the shoes and tubes, and if the tubes are folded, they should occasionally be opened and refolded in fresh places, to prevent the formation of creases. The spare tire that is carried on the car should be kept in a casing, and because a dark surface will absorb more heat than a light, the casing should be tan, gray, or white rather than black. The casing should be as proof as possible against moisture, but for safety should occasionally be removed and aired. The position of the shoe in the holders should be changed every little while, in order that the straps may not cut into the bead.

The tires on the wheels should receive care, and when the car is left standing, it should be in the shade whenever possible, to protect them from the deleterious action of the sunlight in hardening the rubber. They should frequently be examined, and any cuts filled with strong cement, for otherwise water and sand will work in to form blisters and to separate the layers of fabric from the rubber. The cutting of tires can be reduced by withdrawing the clutch when crossing broken stones, the car coasting over them; driving the car over such a surface will force the tires against the sharp edges, and cutting will result more surely than when the tire rolls over them.

CARE OF THE ENGINE

The carbon deposits that will form in the combustion space will in time tend to stick the piston rings in their grooves, and this may be prevented by squirting a few drops of kerosene oil into the cylinders and cranking the engine to distribute it. This should be done at the end of a run, and the engine permitted to stand in that condition. The first explosions will vaporize the kerosene and drive it off unless too much has been used, when there will be a tendency to foul the spark plugs.

The lubricating oil should be drained out of the crank case every five hundred miles, and the case washed out with kerosene before refilling it with fresh oil. Gasoline has too great a cutting action to warrant its use for this, as it cleans down to the bare metal, while kerosene removes the dirt and grease, leaving a good surface. The case should be filled with oil to such a depth that the connecting rods will dip into it from a half-inch to an inch.

The same should be done with the change-speed gear case every thousand to fifteen hundred miles, for the particles of metal that will be ground from the gears will injure the teeth and bearings. In refilling, the smallest gear should project about an inch into the oil. If the differential is packed in grease, it will run for an entire season with one filling, but if it runs in oil it should be cleaned and washed two or three times a year. The bevel gear case of a shaft-driven car should receive the same attention.

CARE OF CHAINS

Properly lubricated chains should run for at least a thousand miles without attention. Because of their exposed position they should be protected against undue wear, and this is best attained by soaking them, when thoroughly cleaned, in melted tallow, working each joint in order that the liquid may penetrate. The chain should be hung up to cool and dry, the surplus tallow being wiped off. The hardened tallow in the joints will prevent grit from working in, and is a lubricant as well. To clean a chain, soak it in kerosene, working each joint to remove the grit. The stretching of the chain may be taken up by lengthening the radius rods, but when the stretching reaches a point that permits it, the chain should be shortened by the removal of a link, and the rods readjusted. If a complete chain is not carried as a spare part, the kit should always include a few extra links for emergency repairs. These are not difficult to apply, being secured in position by nuts instead of by burring over the ends of the rivets.

VALVE GRINDING

To grind a pitted or worn mechanically operated valve, the pressure should be released by compressing the spring and removing the key or other device by which it is held in place. On removing the plug over the valve pocket, the upper surface of the valve disk will be exposed, and it will be found to be provided with a slot. While many grinding pastes may be purchased, good results will be obtained by mixing machine oil with flour of emery until it is thick. Plugging the opening from the valve pocket to the combustion space with cotton waste to prevent the paste from entering the cylinder, spread it on the valve disk and seat, and rotate the disk on its seat with a screwdriver, preferably by means of a bit brace. Every little while the disk should be lifted and replaced on the seat in a new position, in order to distribute the wear evenly, and the grinding continued until a smooth surface shows all around both disk and seat. It is not necessary to smooth the entire surface of the disk and seat, for the pressure will be retained by a narrower surface.

An automatic valve may be removed from the cylinder by unscrewing or unbolting its cage, and after releasing the spring the cage may be held in a vise while the grinding is performed.

After grinding, all traces of the paste should be removed by washing with gasoline, for any particles that remain will cause rapid wear. When replacing the spring, that of the mechanically operated valve will be found difficult to compress to the point at which the key or washer may be slipped into position, and to simplify this many engines are built with a knob or boss on the cylinder to serve as a fulcrum by which a forked lever may be used. If this is not the case, the spring may be sufficiently compressed in a vise, and bound endwise with wire to retain it, the wire being cut when the spring and key are in position.

CARE OF STEERING MECHANISM

A failure of the steering mechanism will cause a wreck more surely and quickly than the breakdown of any other part of the car, and the best protection is absolute knowledge that it is in perfect condition. All joints should be kept well lubricated, and protected from dust; the leather protectors that are furnished do not accomplish this any too well, but they are much better than nothing, and if the joints are packed with grease before applying them, the results will be good. While guarding against stiffness, there should be very little play or lost motion in the mechanism, and the parts should be frequently examined for bent rods and loose joints. A bend in the drag link or steering knuckles will throw the front wheels out of true, in which case the tires will be badly worn. When going straight ahead, the wheels should be parallel; if this is the case, the angles of the steering arms will give the proper track when making a turn.

CARE OF SPRINGS

The springs of an automobile are in constant motion, and should be as carefully lubricated as the other parts of a car. The spring hangers by which the two halves of a full elliptic spring are joined, or by which a half elliptic spring is attached to the frame, are often provided with grease cups, but in the absence of these the parts should be frequently oiled. Once a season fresh lubricant should be applied to them. The leaves of a spring may usually be separated enough for this by jacking up the body, applying the jack to the frame; the springs will thus be relieved of the weight, and the leaves will separate sufficiently to permit heavy grease or graphite to be introduced between them by means of a table knife. If the springs are too heavy to permit this, they must be taken apart, which may be done by removing them from the car and releasing the clips by which they are held together. In reassembling a spring, it may be clamped in a vise, when the clip may easily be secured.

ADJUSTING VIBRATORS

In adjusting the vibrators, the best guide is the running of the engine. The musical tone that they make is misleading, for a difference in the steel of which the blades are made, or in the quality of the core, will produce a difference in the tone, and because two vibrators sound alike is not proof that they are producing equal secondary sparks. With a one-cylinder engine, the adjusting screw may be turned until the engine is running at its best, while at the same time there is the smallest spark between the vibrator contacts. The adjustment of the vibrators of a multicylinder engine is proceeded with along similar lines, all of the blades but one being held down, while the free blade is adjusted until the best results are obtained in the operation of the cylinder to which it corresponds, and the smallness of the spark between the vibrator contacts. When one is correct, it is held down and another released, this process being continued until all are adjusted.

MATCHING COILS

When coil boxes are so built that the units may be removed conveniently, as is usually the case, it often happens that the running of an engine may be improved by matching the coils and cylinders. A difference in the compression in one cylinder will often cause it to run better on one coil than on another, for no two coils will give identical results. Taking each cylinder in turn, and transposing the coil units in the box, the effect of each coil may be noted, and a combination found that will improve the operation of the engine.

ADJUSTING THE CARBURETOR

When adjusting a carburetor, it must be remembered that the proportion of liquid gasoline to air in a correct mixture is very small; because this is not well understood, a rich mixture is present far more commonly than a poor one. To begin at the beginning, close both the gasoline and auxiliary air inlets, and opening the gasoline adjustment a very little at a time, crank the engine with the relief cocks open until combustion is secured, the spark being retarded and the throttle nearly closed. When the engine runs, note the color of the flame that shoots out of the relief cocks. A poor mixture will produce a yellow flame, and a rich mixture a red and smoky flame, with black smoke at the exhaust and a smell of gasoline. The flame of a correct mixture is blue and hardly visible. On securing a correct mixture at low speed, advance the spark and open the throttle to speed up the engine, and the mixture will at once become too rich. Adjusting the auxiliary air inlet by weakening the tension of its spring will bring the mixture to approximately correct proportions. A more careful adjustment under road conditions can be obtained by adjusting the air inlet while the car is being operated, for the position of the carburetor is usually such that this may be done while standing or kneeling on the running board.

Faulty adjustment of the carburetor is often suspected when the real source is in the throttle or governor connections. The bending of a rod connecting the throttle with either the foot, hand, or governor control, or the wear of the joints, will throw the carburetor out, and the possible failure of these parts must be borne in mind accordingly.

SETTING THE VALVES

In setting or timing the valves of a gasoline engine, the point to be considered is the closing of the exhaust valve, for upon this good results depend. If this valve is held open too long, the burned gases driven out will be drawn back into the cylinder, and if it closes too soon the greatest possible quantity of burned gases will not have been expelled. The many experiments carried on by the manufacturers, and the attention that they must pay to this point, result in the delivery of cars with valves correctly timed, and usually with marks made on the two-to-one gears to guide in resetting them. In the absence of these guides, the setting of valves need not be difficult, although experimenting is required to secure the best results. The first step is to locate the position of the piston in the cylinder. There is always an opening in the cylinder head—a relief valve, the spark-plug opening, or other—and a stiff wire may be dropped through it, with its lower end resting on the piston and its upper end projecting. As the piston is moved by cranking the engine, the wire will move with it, and is to be marked with a file at its highest and lowest positions. While no fixed rule can be laid down, it may be said that in general the exhaust valve should close when the piston has made from 1/64 to 1/32 inch of its outward stroke. The two-to-one gears having been unmeshed, the cam shaft may be revolved in its bearings by hand; cranking slowly, move the piston down from its highest point to that at which the exhaust should close, and hold it there. Revolve the cam shaft until the nose of the cam is passing from under the roller of the valve-lifter rod, and the valve just closed. This point may be accurately ascertained by placing a strip of thin paper between the valve-lifter rod and valve stem; when the cam is acting on the valve-lifter rod, the paper will be pinched, but the seating of the valve will release it. When the paper can be pulled out, mesh the two-to-one gears, and the relations thus established between the crank and the cam shafts will be maintained. Cranking the engine a few times, using the strip of paper, will verify results, and the engine may then be started and the effect noted. If the running is not satisfactory, unmesh the gears, and mesh them with a difference of one tooth, first one way and then the other, noting results, and retaining the most satisfactory position. Cams are often cut in one piece with the cam shaft, and the gear keyed on the end; there is therefore no chance to make a finer adjustment than what is permitted by shifting the gears one tooth at a time. On multicylinder engines, one cam shaft operates all of the exhaust valves, and the setting of one valve sets all.

When inlet valves are of the mechanically operated type, but controlled by a separate cam shaft, this must be set in a similar manner. The nose of the cam should just be coming into contact with the push rod roller at the instant when the exhaust valve is completely closed. This should occur as the piston begins to move outward on the inlet stroke, the exact position being determined by experiment.

When the cams are so badly worn that if they are set to open correctly they close too soon, the best remedy is a set of new cams; for while the brazing of a strip of brass to the sides of the cams can be resorted to, the result is only temporary at best, and not as accurate as that secured by the use of new cams.

While the tension of the spring of an automatic valve is sometimes controlled by a nut, its adjustment usually depends on the stretching of the spring to strengthen it, or the cutting off of part of a turn to weaken it. The tension should be adjusted, one cylinder at a time, until the best results from each are secured.

THE WIRING

In laying the wires for the ignition system, only the best wire should be used, and all contacts should be bright and clean. Connections should be tight, and covered with vaseline to prevent corrosion, additional protection being secured by binding all exposed places with so-called electric tape. There should be the fullest protection against chafing and moisture, and no sagging of the wires. Beginning with the battery, the cells should be placed in a box that holds them securely, so that there may be no jolting, for this in working the wires will tend to loosen the connections. In connecting the cells, the wires should be cut to correct length, but not so short that they will be drawn tight when connected. The insulation should be cut off cleanly, and the paraffin that will cling to the metal scraped off. The ground wire may then be run, after which the wires from the two batteries may be connected to the switch. (Fig. 50). On multicylinder engines, one circuit should be completed and tested before another is started, as this obviates the danger of confusing the wires. The primary wire should be run from a coil unit to its timer contact, making sure by the buzzing of the vibrator that the current flows when the switch is closed. A buzz of the vibrator when the timer is not making contact indicates a short circuit. The primary circuit for the coil having been correctly arranged, the secondary connection should be made and tested before laying the primary of the next coil unit. In making the timer contacts of a four-cylinder engine the firing order as established by the opening of the exhaust valves must be kept in mind. With the spark control lever in the retarded position, the timer should be set so that it is just beginning to make a contact when the piston in cylinder No. 1 is at top dead center of the compression stroke. This contact should then be connected to the primary terminal of the first coil, and the secondary of that coil connected to the spark plug. If the firing order is 1, 2, 4, 3, (Fig. 51), cylinder No. 2 will be the next to fire, and the primary of coil 2 should be connected to the next timer contact in the direction of rotation. As the next cylinder to fire will be No. 4, the timer contact that will next be reached should be connected to coil No. 4, the remaining contact point being connected to coil No. 2. In the diagram the timer is supposed to be moving in the same direction as the hands of a watch.

There is no difference in the wiring of a horizontal double-opposed and a two-cylinder vertical 180° crank-shaft engine, as shown in Fig. 50, except that the timers are so built that in the first the two contacts are a quarter revolution apart, and in the second a half revolution.

In wiring a car with a single coil and secondary distributer the four contacts of the timer all lead to the primary terminal of the coil, the firing order being according to the manner in which the secondary terminals of the distributer are connected to the cylinders (Fig. 51).

Wiring for the make-and-break system is much simpler than that of the jump-spark, and when a magneto alone is used, it consists, as will be seen from Fig. 52, of only a wire from the magneto to the igniters, the other terminal of the magneto being attached to its metal base in such a manner that the ground connection is made when the magneto is secured in position on the engine. The firing order is according to the setting of the cams that operate the igniter tappets.

LUBRICATION TABLE.