Side Gap Spark Plugs
 

So from searching;

https://www.gassavers.org/showthread.php?t=681
https://www.gassavers.org/showthread.php?t=163

I searched because I saw this:
instructables instructions

And in my need/want/desire to know "things" - has anyone empirically tested these for FE? That is, dyno's of performance vehicles aside -- has anyone found or conducted an experiment on a regular, non performance, engine?

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SVO... How long did/have your plugs last(ed)?

My experience with side gapping was more negative than positive. I felt that side gapping did make a positive, noticeable difference, initially. I couldn't discern any significant difference in overall mileage, but it did seem to help at idle. However, it seemed to be a very short period of time before the car started not running so well and I had to replace the plugs. The gain wasn't worth the pain, IME.