The Nonpartisan Leader Newspaper, March 10, 1919, Page 10

= LR0Nn : DB e 0ot O O D Finding Trouble in Ignition System Extract From a Pamphlet Put Out by Department of Agriculture on “Hints on Running a Gas Engine” : ECAUSE of the large & | amount of time lost on many farms on account of gasoline engine trou- ble, a recent bulletin. of practical hints on this subject put out by the department of agriculture ought to be of special in- terest to farmer operators. A copy may be secured by writing to the De- partment of Agriculture, Washington, D. C., requesting Bulletin No. 1013 on . | “Practical Hints on Running a Gas Engine.” The following advice on starting troubles, taken from this bulletin, shows the nature of the booklet: . Always bear in mind that for a gas engine to run it is necessary to have a compressed mixture of vaporized fuel (generally gasoline or kerosene) and air in proper proportions, which is ex- ploded by a hot spark while the mix- ture is under compression. The spark should occur slightly before full com- pression, except in starting, when it should occur just after full compres- sion has been passed. When an engine refusés to start, the trouble will, with a very few ex- ceptions, be due to some interruption of the supply of the proper mixture of gas and air, or to a failure of the electrical system which furnishes the spark to fire the compressed mixture. It seldom happens that both systems are at fault at the same time, so the first thing to do is to find out whether one of these systems has ceased to work properly. ~ The ignition system, on the whole, is more dften the cause of trouble than is the fuel system, and it is usually advisable to test this first unless, on account of the construction of the par- ticular engine in question, it is easier to make tests for troubles with the mixture supply. TESTING THE IGNITION SYSTEM With all engines using spark plugs it is comparatively easy to ascertain whether the ignition system is work- ing properly. Simply remove a plug and ascertain that the porcelain or other insulating material on the inside of the plug is not coated with carbon -and that tHe points are properly spaced. One thirty-second of an inch is about the right space for most sys- tems where a dry battery is used. This is about equal to the thickness of a worn dime. A wider gap will often make starting diffienlt, especially when the spark is rather weak or where a high tension magneto is used. In the latter case the best results will often be obtained when the gap is not more than 1-40th or even 1-50th of an inch. Then reattach the wire and lay the plug so that the metal base touches the engine casting, while the end of the wire and the metal tip of the plug’ are at least half an inch from any metal part connected with the engine and in such a position that the points are visible while cranking the engine. Then turn the engine over a few times (at least as many times as there ‘are cylinders) and note whether a spark , jumps across the space between the points. It is-not sufficient, however, | * merely to ascertain if there is a spark —it ‘must be hot enough to fire the i compressed charge in the cylinder. It i I8, of course, difficult to tell by merely {77 looking at it whether the spark is hot enough or not, but if it is a heavy blue, or a bluish-white, or a “fat” .. yellow one looking like a small flame, it is probably all right. If very thin and greenish, or showing red, the | chances are it is too weak to; fire the - R B T N A R e R AT 8 : n g With stationary engines and tractors doing so much of the work on the farm, the problem of efficient handling and general repair ‘becomes increasingly important. .the aggregate for the nation. charge. One may familiarize himself with the aspect of a good spark as follows: ‘ g While the motor is in satisfactory running condition loosen the nut on the top of one plug while the engine is stopped so it will be eéasy to remove the wire from the plug after the en- gine is started. Then start the engine and, by taking hold of the wire where it is covered with insulation, move the end of the wire very slowly away from the center of the plug and watch the spark jump, closely observing its color and thickness. : g It is also well to note the distanc the spark will jump, yet not advisable to force it to jump too great a gap, nor should the end of the wire be al- lowed to rest in a position where the spark can not jump to the plug or the engine while the engine is- running, as this tends to break down the in- sulation of the coil. In the case of high-tension. magnetos there is no danger in this respect, as they are fitted with a safety spark gap which the spark will jump, if for any reason the circuit’ is broken elsewhere. Knowledge of just how much of a spark one should obtain with each kind of ignition system is frequently of great value in locating trouble, and every cne who operates a gas engine should make the above described tests while the engine is in good order. If one is not sufficiently familiar with the looks of a good spark to tell by mere observation whether it is hot enough, a rough test may be made as follows: Place a thin -piece of dry cardboard, such as an ordinary visit- ing card, or three or four thicknesses of dry newspaper, between the points of the plug whilé it is lying on the engine in the position first mentioned, then crank the engine. A good spark will jump through these, leaving a The time lost in getting the engine working is enormous in A careful reading of the booklet from which the extract on this page is taken, would probably save many farmers a great deal tiny hole.- A spark which will not do this is too weak to jump the spark gap in the cylinder under compres- sion. : If the engine is equipped with a make-and-break ignition system, in which an igniter block is used instead of a spark plug, it can be ascertained easily whether the entire system, with the exception of the igniter block, is in good shape by disconnecting the wire from the igniter block and snapping it across the corner of the engine cast- ing or the end of the other wire lead- ing from the coil. But even though this gives a good spark it does not necessarily mean that the spark is given in the cylinder when the engine is turned over. It may be that the points of the electrodes inside the cylinder do not touch each other when they should or are not making a good contact because carbon, oil, dirt, ete., .have accumulated between ".these points. - Therefore, if a good spark “occurs when the wire is snapped across part of the engine, crank the engine until the movable electrode is released and allowed to fly back. OTHER HANDY METHODS If one is not sure just when the points .of the electrode should be touching, the engine may be cranked very slowly for two full revolutions while the end of the wire is repeatedly snapped across its connection on the electrode. If no spark can be obtained at any position of the electrode, it is evident that contact is not being made by the points inside the -cylinder. (This is in case the other wire is grounded directly to the engine.) Sometimes the other wire is fastened to a piece of metal insulated from the engine, but which touches part of the engine for an instant when the spark Farm Mechanic—A New Profession Labor is the great problem on the farm at the present time. War con- ditions and abnormal wages in the various lines of industry have de- -moralized farm help to such an ex- tent that it is exceedingly difficult to get assistance requisite to carry on operations. _In this state of chaos, the federal board for vocational education has hit upon what seems to be a solution, and has created a brand new profession— that of “farm mechanie,” and it is figured that any farm of more than 100 cultivated acres can very well af- ford to have a man of this sort. - The men being' qualified for this work are disabled soldiers who before injury were farm boys. -With this background of agricultural knowledge these men are being taught to oper- ate modern tractors which do the work of many teams and men. They are. -‘u&‘& AR FELTAAAE being taught operation, care and up- keep of motor trucks and other gas ‘engines. They are being given a gen- eral course in looking after all ma- chinery used on modern farms, and indications are that the supply of these specially trained men will not begin to equal the demand. Farm- hands who "before the war could not hope to make more than $25 or $30 a month as laborers can, by becoming proficient as farm mechanics, qualify for positions paying from $100 to $126 per month, with steady employment the year around. : Farm boys who have been discharg- ed and are disabled as a result of their services either by sickness, ac- cident or digsease would do well to write to the Federal Board for. Voca- tional Education, Washington, D. C.,. .and' obtain the particulars of _this training which the government pro- of time and trouble. should occur in the cylinder. In this case, if a spark can be obtained by bringing the ends of the two wires in- to contact it should be determined whether the insulated piece is making contact with the engine properly. If no spark is obtained at the plug or igniter block when testgd as di- rected, it will, of course, be necessary to look over the electrical system in order to ascertain what is wrong, The electrical. systems of various engines differ considerably and no. definite in- struction can be given for different makes, but some general points-will be mentioned. First of all see that the switch is in starting position. Much time has been lost in thousands of cases by trying to start the engine with the switch off. When the engine is one with which the operator is fa- miliar he will, of course, know. the proper position of the switch for starting. In all cases where a bat- tery of dry cells is used, the switch should be closed. - Some engines, how- ever, are started with a spark from a magneto, for which the switch is in starting position when open: - Next, look over all wire connections to see that they are tight and clean. If the engine starts on a battery of dry cells see that all connections be- tween the cells are tight and that no short circuits are caused by the metal- lic portions of the cells touching each other, or by metal connection with the engine, or by tools lying on the cells, etc. The small knurled nuts on" dry cells frequently loosen from vi- bration and thus interrupt the whole ignition system. ; AMMETER HANDY IN TESTING CELLS It is 2 good thing to keep an am- meter handy for use in testing the strength of the cells of a battery. In testing with an ammeter it is best to discard all cells that do not test over 12 amperes. A new cell should test between 20 and 30 amperes. If no ammeter is available, a crude-test can . be made by strikirig the end of a wire _ connected to-one end cell of the bat- tery against the first connection on the cell at the other end. Do not keep the wire in contact with the cell for more than an instant. i Doing so will weaken the battery, but by snapping it quickly across the edge of the knurled nut a few times and noting the sparks, one can ascer- tain whether the battery is producing a good current. By making this test a few times with a battery which is in working condition, one can easily learn about how much of a- gpark should be expected. 'The sparks in this case will not be so intense as those produced at the spark plug by the coil, but when the wire is snapped ~across the milled side of the nut on - bea sputter- - _the dry cell there shoul ing succession of tiny s X A.". e A, )