Arizona republican., 1921-04-03

the unhampered generation of cur rent. the correct interruption of the primary circuit, the free flow of cur rent to the spark plugs and on these latter being properly adjusted to pro duce a good spark to insure good 1g- milton.
 In the case of the battery system it is vitally important that the bat tery shall be kept properly charged and duly filled with water. All con nections must be kept tight and clean If the connections become loose there is great danger of misfiring ensuing if the connections are allowed to be- come corroded it will probably pro- duce misfiring or even failure of the ignition altogether, and hard start ing will certainly be experienced. The wires from the battery to the ignition device must be perfectly in sulated all the time. A broken insu- lation will permit the wire to come in contact with metal at intervals, causing misfiring.
 The interrupted points are another location of possible trouble, and these parts should be separated by about .015 of an inch when they are wide open. Also the points must be kept clean and bright. Should the points become dirty, gummy, uneven or worn misfiring will be fairly sure to result. The distributor arm which turns around and passes the spark to the segments, whence it is carried by wires to the spark plugs, must be clean at the end and the segments also must be clean.
 It is important also that the high tension wires to the spark plugs make good contacts at both distribu- tor and spark plug ends. The cables must be kept perfectly insulated.
 The plugs also are a possible loca- ton of trouble. They must not be dirty at the points, A worn dime usually serves as a good gauge to determine if the sparkling points are correctly separated.
 It is characteristic of ignition trouble that it usually sticks to one single cylinder. This is not always the case, as missing simetimes runs up and down the line. When you have occasion to suspect ignition trouble begin working at the spark plug, after you have located the cylinder that is at fault. Take the plug out and lay it on top of the cylinder. Crank the engine by hand with the switch turned to battery. If the plug fires it is not to blaine. If the spark is weak. however, it may be that it is not strong enough to fire under compression. If there Is doubt as to just where the trouble lies this operation should be carried out on each plug until the guilty one is found.
 To determine which plug is at fault there is no better method than the old fashioned one of the hammer or screwdriver. While the engine is running short circuit the plug by holding the metal of the tube against the top of the plug and the cylinder. If there is no change in the firing of the engine, as told by the sound, you have found the faulty cylinder In the case of engines having sepa- rate exhaust passages for each cylinder it was an easy matter to find one that was not firing by dropping a little water on each in turn. Naturally the exhaust of the cylinder that was not firing would be cool, while the others would be hot.
 After a cylinder has been detected as not firing the first step to take is to examine the spark plug. IT the plug proves up, trace the wiring back to the ignition unit Gum or dirt on the interrupter points should be cleaned off with a few drops of ker-
 
 they may be touched up with a mag neto or jewellers file. If they are toe far apart or too near together, by all means adjust them.
 In the four unit coil system any 1 maladjustment of the coil inter rupters will probably cause misfir- 1 ing.
 In the case of magneto ignition the same general principles hold good as ] in the battery and instructions for detecting misfiring and remedying il are practically identical. In the magneto, however, weakening of the magnets must be guarded against l This will cause misfiring at low speeds, though at high speed the trouble may vanish. Coil connec- tions should be watched, the com monest troubles in the magneto sys- tenn result from loose or dirty con- nections.