Collection, Preservation and Display of Old Lawn Mowers
could someone please tell me why this plug has two contacts around the center electrode??
My understanding is that some engine designs need the ground electrode to be at the side of the central core rather that at the very end of the plug. The downside of this is that the spark erodes the electrodes faster in this position than it does in the normal location, to overcome this and to give a longer service life two or more electrodes are used, this does not mean that you get two sparks though.
Hope this helps