Spark In Time On The Firing Line (1962) Pt 2

[Music] oh and one more thing to suppress radio and electronic interference ignition systems have resistance built into the ignition circuit in the distributor in the ignition leads or inside the spark plugs themselves as long as they are in good condition and operating correctly they have no effect on engine performance now let's take a look at the ignition system in another way all elements of the system except for the spark plugs are concerned with providing sufficient voltage at the right time the job of making voltage available the spark plugs use this voltage and their condition determines the voltage required to relate these two basic functions we need a [Music] graph no get him out of here I said graph this scale represents voltage from 0 to 30,000 volts a typical 12vt ignition system that's new or in excellent condition will make up to 30,000 volts available to the spark plugs while brand new plugs require about 5,000 volts to produce a spark that will jump the Gap the difference between voltages available and required is the reserve strength of the system you might call it a laziness Factor since like a strong man or a super Mouse who can lift his own weight but doesn't use any more strength than he has to an ignition system does not produce any more voltage than is needed to push the spark across the gap between the plug electrones however sudden acceleration increases voltage Rec requirement sharply ignition systems in top condition have plenty of Reserve to handle these sudden loads but as plugs are used the electrodes wear and the Gap opens wide by the time they've run about 10,000 M the electrodes are burned and worn and voltage requirements have doubled and if these plugs are not replaced voltage required keeps going up until sudden acceleration increases requirements above availability and the engine misfires replacement with new plugs will restore the reserve Factor but there are other conditions which can affect voltage requirements the sparking end of a plug Works where it is constantly exposed to oil and the products of combustion deposits may form on the insulator which if allowed to build up heavily give the circuit an easier path to take at a much lower lower voltage this spark plug fouling causes the engine to misfire because there is no spark to ignite the fuel a condition where voltage required being so lazy it only works as hard as it must to complete the circuit doesn't build up the voltage required for sparking we might also mention that if the primary leads to the coil get switched reversing polarity voltage requirements will be increased about 40% which on top of any other adverse factors can soon cause trouble unless corrected once again we have first developed a situation as if for a one-cylinder engine to get the complete picture voltage requirements for each cylinder would have to be recorded separately just as is done on Modern electronic oscilloscopes such as the plug scope which simplify the job of checking ignition systems with a graph or trace for each plug any condition which affects voltage requirements will be reflected on the proper bar for instance if a plug has too wide a gap its Trace bar will show an increase in volage requirements in this case bringing it above the reference line a definite indication of unsatisfactory ignition performance on the other hand if a plug is fouled its voltage required would drop since what we actually see is the voltage required to leak to the ground lower than what is required to jump the spark gap on the scope then we can compare voltage requirements for all plugs voltage available can also be observed and compared by disconnecting any of the plug leaves thus forcing the lazy ignition system to put out as much voltage as it can then we have a direct comparison of available and required if voltage available is lower than it should be it is apparent that the ignition system should be checked for TR trouble it could be that the breaker points are spaced too far apart making the dwell angle too small it could be the condenser if it is not properly matched to the system it can cut down voltage available and also cause transfer of metal at the points the induction coil may be partially shorted dirty or burned contacts or connections may be cutting down voltage available so as time passes and the ignition system is given a harsh and hectic workout there are many ways in which available voltage can be reduced while voltage requirements creep up [Music] until our once strong system is sick and the load it must bear is beyond its ability [Music] of course major illness often can be prevented by looking for early symptoms before the illness becomes serious by periodic checkups and tuneups something car owners seldom think of themselves unless it is suggested to them [Music] [Applause] la