1910 - Making A Spark Plug

Why are spark plugs so much fun to look at?  

I think they snap into our far from buried childhood impulses to collect small, cool looking things. 

If you were the sort of kid who really prized certain pebbles because of particular "features", this article's illustrations will probably catch your eye.  I suspect a fair number of today's Pokemon besotted children will fall prey to the spark plug's siren call as well. 

Then again, the names of the individual plugs are amusing enough to catch the ear of another sort of collector!

And, of course, the engineering of the physical plug deserves our interest and respect...with the more "interesting" variations making for amused contemplation.    

Finally, there is the advertising!  That can be a lot of fun.

After thinking about it, it seems odd that everyone isn't interested in spark plugs. 

This article was poorly scanned so I have used plain text instead of the scanned printed text.

A  SPARK plug is a simple thing, surely —just a threaded plug, an insulating core and a bit of packing. These are its elements, in the abstract, and are all that arc needed for the introduction of sparks to a closed chamber. However, when this chamber is provided with a moving piston that must be generously lubricated, is filled with flame for from one-quarter to one-half of the time, and is subjected to pressures varying almost instantaneously from somewhat below atmospheric to upward of 400 pounds per square inch, the qualifications that must be possessed by these simple elements become many and varied, though their ultimate function remains unchanged and one of the simplest imaginable.

To begin with the simplest of the conditions to be met and rendered innocuous, the widely and suddenly varying pressures are taken care of by non-porous and rigid parts with interposed packing of a semi-rigid character, such as asbestos, copper, or a combination of the two.  Semi-rigidity in the packing is made necessary because of the relationship that must be maintained between the threaded plug body or an attached part and the inserted core or one of its attached parts. Furthermore, this packing must be capable of withstanding great heat without deterioration and of absorbing and compensating within itself any expansion or contraction of the other and rigid parts due to temperature changes. Our "bit of packing" must embody some quite special characteristics!

From the very nature of things, the insulating core must be quite special. In the first place, it must retain its insulating ability against high pressures and high temperatures. Immunity from pressure breakdowns is easily had through the use of a non-porous insulating material, but like immunity from high and varying temperatures is not so easily had. To be non-porous, the core must be rigid, and to be a perfect insulator and rigid in the presence of alternating high and low temperatures is to experience severe internal stresses tending toward fracture. All cores are tubular for the adequate insulation of the central electrodes which are of necessity metallic, and, besides the internal stresses, the cores are subjected to those of external application, due to the "coming and going" of the electrodes and the plug bodies.

Even so, a uniform cross section for the insulating core would largely relieve it of the effects of both internal and external stressing, but such a shape is impracticable because of the necessity for surfaces against which packing can be applied. This really very great difficulty is only overcome through the use of insulating materials having very approximately the same coefficients of expansion as the surrounding and contained metal parts.

Now we come to the chiefest of all problems in the plug's construction—a further problem of insulation. The before-mentioned piston must be lubricated, and lubrication requires oil. Oil in itself, high grade gas engine oil, that is, will not impair a plug's insulation. But no oil can retain its original qualities and chemical purity in the presence of such temperatures as are utilized within the motor car engine's cylinders. It becomes broken down chemically, and, if supplied in even slight excess, leaves a conducting deposit on all surfaces with which it comes in contact. This deposit of conducting material, practically free carbon, is further aggravated by even a slightly over rich mixture. This deposit over the insulating surface between the plug's electrodes, of course, prevents the spark from jumping, through providing an easier though longer path.

It is the combination of these circumstances that is accountable for the many different forms given those parts of a plug that project into the cylinder.

In some cases the insulating surface is protected by a partial enclosure, in others it is made as extensive as possible and so placed that deposits cannot readily reach it, and in others it is protected by baffles, and in still others is located within a "combustion chamber" into which some of the mixture is compressed, and from which it rushes, past the sparking points, when ignited. In all plugs, the insulating material serves simply to artificially create a more or less wide insulating air gap, the most effective known insulator.

The corroding or burning action of the spark from a high tension magneto upon the electrodes at high speeds complicates the problem of maintaining the necessarily short spark gap. Probably the greater number of plugs have at least one electrode that can be set by bending to give a proper gap: in others the gap length can be adjusted by special means without removing the plug from the cylinder. Other magneto plugs have multiple gaps, either set at varying lengths or all initially of the same length. The gap of the least effective length is of course selected by the current, and the rate of the burning away is therefore minimized, referred to the whole plug.

Let us not say of the spark plug, "Oh, most simple."

• #1 - "Ball", Ball Multi-spark Plug Co.
• #2 - "Point" - Point Spark Plug Co.
• #3 - "National" - National Coil Co.

• #4 - "Volcano" - Volcano Spark Plug Co.
• #5 - "Lemke-Briggs" - Lemke-Briggs Elec. Co.
• #6 - "K-W" - K-W Ignition Co.

• #7 - "Superior Double" - Superior Motor Specialty co.
• #8 - "Fry" - Fry Mfg. Co.

• #9 - "Fenton Double" - Sagamore Motor Supply Co.
• #10 - "All-In-One" - Buffalo Carbureter Co.

• #11 - "Excentric" - Mica Core Mnfg. Co.
• #12 - "Cincinnati" - Cincinnati Spark Plug Co.
• #13 - "Flash Light" - Jamney Steinmetz & Co.

• #14 - "Never-Miss" - Never-Miss Spark Plug Co.
• #15 - "Rayo Conqueror" - O.K. Mica Core Co.
• #16 - "Schenectady" - Schenectady Spark Plug Co.

BELOW: (For some reason the article switched from drawn illustrations to photos.  Photos nice for 1910!)

#1 - "Sta-Rite" - R.E. Hardy Co.		#7 - "X.I.C.R". -  Excelsior Supply Co.
#2 - "Reliance" - Jeffrey-DeWitt Co.		#8 - "U & H" - J.S. Bretz Co.
#3 - "Red-Head" - Emil Grossman Co.		#9 - "Perfex" - Electric Goods Mfg. Co.
#4 - "Wico" - Witherbee Igniter Co.		#10 - "Hades, Jr." - Igniter Appliance Co.
#5 - "Edco" - Ch. Dien		#11 - "Auburn" - New York Mica & Mfg. Co.
#6 - "Delta" - Delta Mfg. Co.		#12 - "Legnard" - Legnard Bros.

#13 - "Ideal" - Ideal Switch Co.		#17" - Quick Action" - Knoblock-Heideman Mfg.Co.
#14 - "Hagstrom" - Hagstrom Bros. Mfg. Co.		#18 - "Rajah" - Rajah Auto Supply Co.
#15 - "A.C." - Champion Ignition Co.		#19 - "Volts" - Buffalo Ignition Co.
#16 - "Blue Blaze" - National Steel Products Co.		#20 - "Lehman" - J. H. Lehman Mfg. Co.

BELOW:

#1 - "Monarch" - E. M. Benford Mfg. Co.		# 7 - "Soot-Proof" - C.A. Mezger
#2 - "Power" - Motor Car Equipment Co.		# 8 - "American" - American Coil Co.
#3 - "Bougie-Mercedes" - Herz & Co.		# 9 - "Winestock" - Knapp-Greenwood Co.
#4 - "Bosch" - Bosch Magneto Co.		# 10 - "Auto-marine - Legnard Brothers
#5 - "Burnham" - Burnham Spark Plug Co.		# 11 - "Dow" - Dow Mfg. Co.
#6 - "Jewel" - Pittsfield Spark Coil Co.		#12 - "Breech-block" - Earl Canedy

# 13 - "Success" - Wait Auto supply Co.		# 18 - "Vanguard" - Vanguard Mfg. Co.
# 14 - "Westchester" - Westchester Appliance Co.		# 19 - "Eisemann" - Eisemann Magneto Co.
# 15 - "Best" - Best Ignition Equipment Co.		# 20 - "Indian" - American Machine Co.
# 16 - "Reflex" - Reflex Ignition Co.		# 21 - "Common-Sense" - C. F. Splitdorf Co.
# 17 - "Spit-fire" - A.R. Mosler & Co.

article from 1910 - Motor, Volumes 13-14