Nine Meadow Lane, North Caldu/ell, New Jersey 07006
The box under the table held strange looking objects with porcelain tops. If these were spark plugs, I questioned why the petcocks... and the springs... and the little windows. There was a whole new world in that box and my bride of three months shook her head at my lingering interest. The sign said '25 and 50'. The vendor leaned over the table and said, 'They're all a quarter'. I was hooked!
That started a 25 year hobby... and thankfully, it's just as interesting today as it was then. Prices are higher, but new and different spark plugs turn up at almost every meet. Spark plugs are generally discarded when they are changed today, but most early plugs could be disassembled for cleaning. And they were expensive! A good spark plug sold for $1.25 in 1910, the same year you could buy a colt revolver for $13.50 or a pair of shoes for about $2.50. It was natural to save and clean spark plugs! They're still hiding in barns and garages and part of the fun is digging them out.
So many different spark plugs were produced! Over 4,000 brand names are known to collectors. No doubt many were 'private branded' by the larger manufacturers, but between 1900 and 1925 there were probably 1,000 different companies or individuals who manufactured or assembled them from parts.
In truth, the history of spark plugs parallels that of early gas engines and automobiles. It was a marvelous era. Technical developments poured out in profusion. Every manufacturer seemed to have his own idea of 'improvement' and took it to the marketplace with much fanfare. Early advertisements give a good idea of what was available and also the competitive atmosphere. Advertising was in its heyday and many ads made claims far beyond reality; truthful or not, they make great reading. A friend suggests, 'They had the ethics of weasels, helping themselves liberally to each other's technology; if not patented, they marked it patented just to claim superiority'.
The names themselves speak of the variety: Barney Google, Bald Head, Spit Fire, Inferno, Blue Blaze, Fan Flame, Home Run, Kantfoul, Sure Pop, Hire Fire, Bulls Eye, Ezekleen, Raccoon. But it's the mechanical gadgetry that intrigues most collectors. Some features had real value; others were destined to oblivion as soon as the consumer passed judgment. Spark plug collectors tend to classify plugs by their features; there were primers, quick detachables, self-cleaners, breathers, visibles, 'intensified' plugs, series plugs, double-enders, and those of special interest, perhaps because of shape or color.
Priming plugs were fitted with pet-cocks or valves for the direct addition of a little gasoline or ether for cold morning starts. Some priming cups were tapped into the sides of the plug while others were mounted up top and primed through the center of the porcelain. These 'top primers' often had brass funnels and some allowed withdrawal of the center electrode for cleaning. When polished, they really dress up an early engine.
In this day of improved gasolines, priming may be a lost art. There is an oil field engine near Wooster, Ohio, that refuses to start without a 'warm head'. On cold winter mornings, the operator actually builds a wood fire under the overhanging cylinder. I have often wondered if a priming plug wouldn't save all that trouble.
'Quick Detachable' plugs could be disassembled without tools while still in the engine. They generally had handles that could be twisted to allow removal of the porcelain for cleaning. Before reassembly, the cylinder could be primed right through the plug body. Some were complex and beautifully machined; today, the cost of manufacture would be absolutely prohibitive! Most had shortcomings beyond their high cost; carbon deposits would soon encrust sealing surfaces rendering them 'leakers'. The more frail designs were subject to distortion, especially if the engine man had arms like Popeye!
Spark plugs with external spark gaps or 'intensifiers' were said to burn through oil on the points. Although controversial, I am told that intensifiers really did work. The coil had to produce higher voltage to cause 2 sparks in series. The spark across the external gap allowed higher amperage to cross the working points and the heavier spark improved performance in oil-slinging engines. The theory is still applied today; modern 'ignition wires' are actually resistive carbon tracks... they generally contain no metallic wire. Intensified spark plugs often had little windows to observe the external spark and some had magnifying lenses to improve visibility.
'Self-cleaning' spark plugs are among the most interesting in terms of unusual construction. Some had fans for electrodes which were said to rotate and present new firing surfaces. They were supposed to produce a 'swath of flame' and 'blow away the soot'. .. sadly, few worked. One self-cleaner that may have worked is the Myers plug. It contained about a dozen little porcelain balls that rattled about, dislodging carbon deposits. The Wellman-Howe Push-Clean had a spring-loaded center electrode fitted with a coarse-toothed file. By pushing the electrode up and down, the file chewed off carbon buildup. The Wellman Turn-Clean had a knife blade on the center electrode. By lifting and turning, the blade was said to scrape carbon from the porcelain. Some had ball bearings for electrodes that were caged to maintain a fixed gap, but could roll and bounce about, cleaning away carbon while the engine ran. The Schlect Sliding Gap plug had a small metal 'bowtie' on the center electrode that could slide up and down; the 'Movie' spark plug had a heavy sliding electrode with spiral grooves to provide rotation. Alas, not many lived up to the fanciful claims.
Visible spark plugs had translucent 'porcelains' or clear glass windows to permit observing the color of the flame in the cylinder. By adjusting the carburetor, the engine man could get an efficient blue flame... but regrettably, few engines were up to such scrutiny. The big straight 8 automotive engines were particularly unresponsive. If the carburetor was adjusted to produce blue combustion in the center cylinders, the end cylinders usually burned orange. And if the end cylinders burned blue, the central cylinders likely burned orange. These diagnostic plugs simply exposed the inadequacy of carburetion! And that spelled the doom of visible plugs. Still, these make fabulous plugs for running an engine at night. The flash of combustion is a real eye-catcher!
Breather plugs were designed to admit a little air during the intake or suction stroke; the air was said to lean the mixture and cool the points, saving gas and 'improving performance'. The spring loaded inlet valves on used plugs are usually clogged with oil and soot, telling of their shortcomings. Ironically, while the virtues of 'cool points' were touted by some manufacturers, other companies provided long reach electrodes to ensure 'hot points'. The truth is that people didn't know what they wanted, nor was there, a unified understanding of what was best. Different brands of plugs actually provided different 'heat ranges' and the engine man selected a suitable plug by experimentation.
Another idea to improve combustion was to provide two or more simultaneous sparks in the cylinder. If one spark could ignite the mixture, two had to do it better. Some plugs had double gaps in series; others were designed for engines with two separate spark plugs in each cylinder, passing the hot lead to the second plug before grounding the spark. 'Dual Ignition' plugs allowed the choice of magneto or coil ignition at the operator's discretion.
'Coil plugs' had the coil built right on top of the plug, doing away with the hot wire altogether. It is said that early converts to mechanical power had a certain fear of electricity.. . and being zapped by the spark plug wire surely didn't help! Most coil plugs were used on marine engines where absence of the moisture-sensitive hot lead was a real benefit.
Among the most unusual appearing plugs are the double-enders. These had two 'working ends' at opposite ends of the porcelain. When one end failed, the operator simply reversed the plug, presenting fresh points and clean porcelain. Some were 'last gasp' attempts to keep failing companies alive, but as the public gained knowledge through the 20's, these gadgets and gimmicks disappeared.
Many companies failed during the 'Great Depression' and very few survive today; much of the actual history has been lost in the quiet of bankruptcy and corporate consolidation. Every now and then an 'old timer' who worked for Splitdorf (remember the green insulators?) or Benford will talk about 'the good old days'and there are some members of the Spark Plug collectors of America who specialize in brand name history. But for most of us, spark plugs are simply a way to increase our enjoyment of early gas engines or automobiles. We collect to display and talk about the way things were. Spark plugs are a pleasant 'add-on' to seek out while away on vacation .. . and we have something to look for while Mama browzes through the pressed glass at the flea market.
As you complete the restoration of your latest gas engine, why not consider an authentic spark plug? The originals rarely had ribs on the insulators and almost never sported cadmium plating. Don't be concerned with heat range; display engines generally do little work. And don't even be concerned about proper reach as long as the piston passes top dead center without interference. If the insulator is sound (no cracks), the plug will probably run just fine. You will need an appropriate disassembly wrench and a little gasoline or solvent to periodically clean out soot and oil.
Should restoration be required, beware of high speed wire wheels. Some brand names were 'top' printed and not protected by the glazing on the porcelain. The inks are usually resistant to gasoline, but a wire wheel can cause damage. Also, brass parts are subject to smearing or 'orange-peeling'; it is better to disassemble a plug before using a wire wheel to remove stubborn rust.
In disassembly, use a pair of box wrenches, one for the gland, one for the body, to avoid buggering the plug. If necessary, soak the gland in penetrating oil before applying much force. This might seem like common sense to engine restorers, but metal parts were often thin and subject to distortion.
A good rub with steel wool and oil is often restoration enough for metal parts. If a wire wheel must be used for cleaning or blending surface texture, use a fine wire wheel at low peripheral speed. A four-inch wheel at 1725 RPM is more than adequate. Do your best to clean carbon from the porcelain and don't worry about discoloration near the electrodes. Reassemble with just enough torque to get a good seal, set the gap from .020 to .025 to accommodate a possibly weak spark, and you're ready to go!
Spark plugs rarely 'wear out'. Cleaning will generally restore them to good operating condition and you should not fear using them. Your engine will be more interesting ... and as the ad says, you will be too!
For information about the Spark Plug Collectors of America, write the author at: g Meadow Lane, North Caldwell, NJ 07109, or SPCOA, P.O. Box 2229, Ann Arbor, MI 48103. All letters will be answered.