A bit of history for those interested in such:

https://www.hagerty.com/media/automotive-history/how-albert-championed-two-major-spark-plug-brands/?

Wow that is cool. I always wondered where the AC came from.

I've always like the trivia question "what part has always been metric dimensioned on an automobile?" Spark plugs.

On that note "What's the most common thread and pitch in the world?" And why is what threads onto it is it most times missing?" And for some time the 14mm X 1.25 pitch spark plug was the other most common thread.

Twist off caps on 2 liter bottles?

Hmmmmmm good guess but not it. Now think of how many cars, light duty trucks, bicycles, motorcycles TIRES, TUBES, etc., there are in the world and think of how many have a Schrader valve and valve cap that has been the same for decades and decades around the world. (again a metric spec, why? I don't know?) That's a beer in any trivia contest


The standard Schrader valve has the following threads: External thread Metric: 7.7 mm OD, thread root diameter is 6.9 mm × 0.794 mm pitch. Imperial: 0.305 in OD, thread root diameter 0.271 in × 32 tpi (threads per inch) Internal thread (to accept the threaded valve core) Metric: 5.30 mm OD × 0.706 mm pitch Imperial: 0.209 in OD × 36 tpi.

Way more 2 liter bottles than tires or tubes.

Studies show that people around the world buy a total of one million plastic bottles per minute. That’s almost 1.5 billion plastic bottles per day.

Okay "uncle" bottle caps it is and not only 2-liter bottle caps, less ounce/ml bottles use basically the same caps.

Now back on topic.

Looks like fine wire ground electrodes are better than fat ones for a good spark. Probably they made them bigger to get longer life out of them and most likely from consumer complaints and the competition claims of longer life as compared to another brand. Fine wire and precious metal center electrodes are still better for spark plug performance IMO.

Is this a little irony or am I reaching? Note the town that AC spark plugs was (is??) manufactured in on the box FLINT, Michigan.


FLINT :

a piece of flint used with steel to produce an igniting spark, e.g. in a flintlock gun, or (in modern use) a piece of an alloy used similarly, especially in a cigarette lighter:
"he struck a light with his flint"

Wow,
those early industry pioneers
squabbled as much as Moparts members....

DID NOT!

4 Degrees here @ 9"00 am

Mike

5 degrees here at 11:21am.

Ever see a Champion spark plug with a fine wire ground electrode and a silver center electrode like this?

That looks like a surface gap plug that someone modified.

Nope not self-modified but direct from (friend Jerry Grant RIP, 1st Indy driver to go 200+ MPH) Champion Spark Plugs (Toledo) from a handwritten Indy logbook. When I asked Jerry if I could get a couple of these N-S 501 plugs he asked me where the H377 I found the number as he had to go back to handwritten Indy logbooks to find them. I told him an elder factory engine builder for a company I worked for told me to try and find them for a race engine I was building, Jerry found a few boxes left and sent all of them to me. This was back in the early/mid '80's.

I sure would think you would want those plugs indexed correctly in the cylinders. Was there a mark on the outside indicating where the ground strap was located on the plug?

Never noticed one but I agree with the correct indexing. I'll take a look and see if the N-S 501 has some reference as to the ground electrode location??

as Linda Ronstadt used to sing:

Silver electrodes and Golden groundstraps cannot spark this heart of mine....

Hmmmmmm, I wonder how much silver is in each one of those N-S 501 Indy Champion spark plugs and what it be worth? Naw I wouldn't do that, would I