Spark-filled History

| July 2006


A Vital plug, made in Cleveland, Ohio. This is a rare primer plug with 1/2-inch pipe thread.

Question: Which product of the internal combustion age was produced by more than 3,000 manufacturers in the United States, bearing more than 6,000 brand names and covering many hundreds of patents? If you answered gas engines, you would be wrong. The correct answer is spark plugs! Perhaps no other product associated with the dawn of the gas engine was made with such a variety of different ideas as those about the "ideal" spark plug.

Driven by the need to prevent fouling of spark plugs by early gas engines, which consumed oil rapidly, manufacturers tried a vast array of cleaning schemes such as quick take-apart plugs, which could be taken apart, cleaned and reassembled by hand, while the engine was still running! Others tried different designs of electrodes and insulators to keep the plug from fouling.

Another problem was the difficulty of starting early engines, especially in cold weather. This resulted in a large variety of primer-type spark plugs, which allowed priming of the cylinder(s) with gasoline. And other plugs were designed to assist weak ignition systems with built-in spark intensifiers. Still other designs incorporated dual non-grounded electrodes to use in multiple ignition type engines, (i.e. battery and magneto) or dual plug systems from one ignition source.

In the years of approximately 1900-1930, it seemed like anyone who owned a machine shop or factory making products out of metal wanted to get on the spark plug bandwagon. Ceramic companies such as Frenchtown Porcelain of Frenchtown, N.J., and others, who were able to supply the porcelain cores for the many small spark plug producers, made this easier. They only had to machine the brass or steel bases and packing nuts and they were in business.

Another way was to use a stack of compressed mica washers and not risk the easily broken early porcelain. Those of you who have rebuilt low-tension igniters for gas engines are familiar with this.

We gas engine and tractor collectors can surely appreciate the fascination of spark plug collecting, and let's not forget the go-alongs such as the signs, advertising, display cabinets, etc.