My dad who was quite logical in his thinking, and did a lot of tinkering in his shop, and even patented some of his ideas, once asked me this question, "Do you understand all you know about what you are doing?"

Bill Hoddinott recently made a profound statement which all who have built high performance internal combustion engines realize, that if the start of the power cycle, which is the igniting of the fuel with a spark, does not adequately do it's job, performance on the highest volumetric efficient engine suffers a great deal.

A few words on what we know about the visual inspection of a spark. First color of the spark determines how much heat in BTU's is being developed. This can best be explained by firing up your cutting torch, first a yellow flame, and as more oxygen is applied to the available fuel the flame turns blue, and adding even more oxygen turns the flame to a white blue color. This proves that the ignition spark is it's hottest and contains more heat when a whitish blue spark is obtained. The size of the spark is in proportion to how much volume of heat is available to ignite the fuel.

Now that it's clear as to what we know, which is elementary, on to what we understand, which is not brain boggling but not elementary either.

A coil's purpose is to change low voltage into high voltage. A unit could be constructed to achieve 35,000 volts, say without the use of the physics of a coil; however, it would take a battery that would contain 17,500 cells and wire the size of your arm to take the E.M.F. The unit would be about the size of a house and would weigh tons, hence the coil seems to be the better way to go.

What are the components that are required to make a coil? They are a metallic core, a few turns of insulated heavy gauge (usually copper) wire around the core, which is called the primary winding, many turns of insulated copper wire, small gauge, wound inside the primary windings. This is called the secondary windings.

How the coil components work: The low voltage or primary circuit has a flow of current going through it when the points are closed, or in an electronic ignition system a circuit is completed and the ignition switch is on. The primary winding is saturated to a varying degree by the OHM resistance of the primary circuit, the dwell, or time the primary circuit has current flowing through it, and how many times the circuit is being completed; i.e., at an idle of 1000 rpm the circuit is completed 500 times a minute on a four stroke engine. Therefore the circuit is completed more times at higher engine rpm.

So what we have going on is first a saturated primary coil that varies at different rpm due to the fact that a fixed circuit with the size of the primary wire being the factor, bumped against the time factor current is flowing through it. This changes the amount of heat in the wire itself; as the wire heats up it's resistance increases. At higher rpm the primary circuit is cooled due to the real time that current is flowing through the circuit.

With all of this talk you're probably getting a bit bored, so I will get on with what happens next. When the primary circuit is complete it produces a magnetic field around the secondary windings. When the circuit is broken the magnetic field collapses. A magnetic field of flux crosses the secondary windings. The voltage in the secondary would melt the secondary windings if there were any appreciable dwell of the magnetic field of flux crossing the secondary windings. The secondary windings magnetic field collapses and the high voltage around 35,000 volts has to go somewhere, hence that spark you're observing is the voltage crossing an air gap of the spark plug electrode going to ground.

A couple of bits of not so superfluous information. As coils are produced by virtually all industrialized nations for their purpose. This does not mean they're equal in performance. First and foremost is the material that they're made of. The best copper wire comes from Chile. The best wire insulation is made by Westinghouse, and the best encapsulating material comes from Dupont. This, coupled with the fact that there are more performance engines built on a daily basis in the USA than all of the rest of the world combined, keeps such things as performance coils in the forefront, where research, development, is so necessary for a company such as Dynatech to be competitive in a never ending battle for market share. The racer mentally has to be satisfied. What ever works best, sells best.

In about two weeks I'll be putting together the components of the ignition system of the Vincent streamliner known as Black Lightning/Lambky's Liner. This is what I'll be doing. The most important thing to do is to establish the OHM resistance of the coil. Several things must be considered to come up with the right choice.

One thing to consider is, where does the benefit of primary coil saturation end? This is where the current being pushed through the primary coil, which is controllable, becomes so great that the coil winding heats up the coil to destruction. Most of you some time in your life have left your key on in the old run about, setting in the drive. The points by happenstance were in the closed position and the current from a fully charged battery flowed freely through the primary coil, and was not being circumvented from time to time to give it a cooling down period. Hence the primary winding heated up due to the inherent resistance that all coils have. The heat from the winding, by convection found it's way to the secondary windings which were well unsuited to take the heat abuse due to it's small wire size. The only relief the coil was getting from the melt down was the convected heat finding it's way to the surface of the encapsulation cocoon and by radiation, transferred heat to the ambient temperature of the atmosphere. Heat traveling from hot to cold.

So knowing what can happen when coils are overheated, it's wise to keep the coil cool enough so melt down doesn't occur, yet saturate the primary winding so when the highly saturated winding is collapsed the optimum magnetic field of flux is created, which in turn creates the optimum saturation of the secondary winding, and when collapsed gives me that 45 to 50,000 volt blue white spark.

When building your ignition system it is paramount that you keep all of the above basics in mind. To put it simply it isn't rocket science as some would have you believe. It's nothing more than a juggling act, getting the lowest OHM resistant coil in your circuit that will live. Using a coil of quality that can stand some current on the primary, liquid cooled coils are good, cooling fins on the encapsulating cocoon of the windings are good.

One other thing. That old wive's tale that a higher compression engine needs more spark to jump the air gap of the plug is utterly nonsense. May your spark be a whitish blue--you'll need that to get the checkered flag.