I like the look of Edison Spark Plugs and the historical significance of them in that Thomas Edison was one of Henry Ford's best friends, along with Harvey Firestone and John Burroughs.
Are Edison #14 Spark Plugs the only size Edison Plug that can be used in a Model T? Jim Patrick
Hey there Jim P! The number 14 Edison plugs fit a model T, and are fairly common (relatively speaking). They look great, and have the wonderful historic Edison connection to Henry. They are also only a single spark spark plug with a single path pair of electrodes (don't get started on the whole cathode/anode thing, Model Ts are in a world of their own). Most spark plugs ARE only single path spark.
However, the Edison number 13 also fits the model T. They are a bit more rare, considerably larger on the base, and the base has two electrodes instead of one. Both acting on the same single insulated electrode inside the porcelain.
The theory was, that the dual path created double the spark, fired the charge in the cylinder faster, and gave more power. Quite a few companies made "dual spark" plugs back in the day (someone even tried to market the idea about forty years ago for (then) modern cars). The idea, however, is mostly snake oil. The reality is, that usually the spark follows whichever path has the least resistance, and only sparks one side most times. They tend to alternate sides, as sparks burn off material from the electrodes, and the gap widens. Eventually the wider path becomes the higher resistance, overcomes the accumulation of soot and oil on the other electrode, burns it off and the other side fires for awhile and the driver never notices the change. Even if the spark does jump both paths occasionally, the two sparks are so close together that the ignition of the cylinder charge acts the same as a single spark anyway.
The dual fire plugs probably do last a little longer, but otherwise do not really help much. They ARE , however cool to look at, and sometimes a good conversation piece.
So both the 13 and 14 Edison plugs do fit, and work, and actually look good.
Finding matching sets can be a bit difficult. I had eight of the number 13 plugs a long time ago. Unfortunately, I used four of them on a car I had, and let them go with the car when I sold it. Later, I discovered one of the four I had kept had a broken porcelain (probably had been that way for a long time). I have bought several other number 13 Edison plugs, unfortunately, I have not yet gotten a matching set of four to use on a single car. I also have a few number 14 plugs. Same problem. I find others, but they are just slightly different.
These are a two of the Edison plugs I have, shown with a common F-11 model T plug for size comparison. One of the Edisons is turned to show the dual electrodes. (Sorry for the poor quality of the photo)
I think they are a great little bit of additional history to go with our cars.
Drive carefully, and enjoy! W2
A play on words....Edison plugs now in Edison's NJ car....
If I recall correctly, these came through Mike Bender? (Bob may have better memory)
An Edison 13 can be viewed here:
Wayne's three rib Edison with capital letter script I've not seen. Perhaps post Model T era production?
Wayne, that's "fake news" there's a huge advantage in having plugs with 2 (3 or 4) electrodes. They give a psychological advantage to the driver knowing that he's "better equipped" than others on tour, especially against the penny pinchers running Motorcraft or Autolite It's sort of like the placebo effect in medicine.
There are also Edison-Splitdorf plugs. I know someone with a NOS 1/2" set of these.
Must be a Model K, it's running a 6 cylinders. Great graphics!
Wayne, If they are "fairly common" why am I having such a hard time finding a set?? Where to look? I've been checking ebay.
George..... That was a few years ago.... Huh, remember ???? Running a set of #14's in our '26 , b urn clean, no problems.
Marty should try the spark plug collectors for a set ???
Send me a message off Forum please. Thanks
I did get my sets of Edison #14's from Don McKinsey years ago...
Marty B, I DID say "(relatively speaking)". And as Constantine mentioned, I have long suspected that my "three rib" Edisons are slightly later, most likely early '30s.
Full sets are out there. I have seen a few on eBad in the past twenty years, but have not had the money to want to spend for them. I have picked up a few 13s and 14s as individuals for cheap, but not gotten another matching set since I let the set I had go on a car about twenty years ago. There seem to be at least three variations of both the 13s and 14s.
I really like the look of the Edison Splitdorf plugs, I have seen pictures of them before, but never had one.
drive carefully, and enjoy, W2
George & Bob -- Bob bought a set of Edison 14's from me a few years back. He said he wanted them to go into Edison's car.
Bob, sent and thanks.
Wayne, I know, that's why I said "relatively speaking." I figured I could eventually get a complete set by getting at least one at a time. I'm still a-lookin'!