Hey fellas, got bored today and thought I would try and see if I could find any differences between spark plug brands performance speaking using a Merc-O-Tronic 98 to measure the amperage through the plug. This test is for ignition coils, but I had reasoned that maybe when a spark plug was added that it could be measured. An automotive coil was used as that much testing on a small coil is quite hard on it. So I dug out every kind of plug I could find in the shop, the usual suspects and the not so usual. NGK, Bosch, Champion, Torch, Autolite, E3, Husqvarna, CDX, OREGON and even a Briggs & Stratton.
So I got a base line measurement with just the coil then went the plugs one at a time. After I finished and was looking at what I had wrote down, I could see some were high and low. After thinking on it, I realized that the gap was affecting the results, so I re-did the entire test but this time instead of letting the plug spark, I put the test wire right on the electrode. Now thigs leveled right out pretty much even. So looking at the results I took a gap gauge and just like I thought, it took more amperage for an increased gap, and less for a smaller one. Seemed pretty reasonable to me, what I also found though was that most had not changed one bit. These were all to measure exactly .020" . For whatever electromological reason jumping at .020" is unchanged from not jumping at all. So to my line of thinking, this must have some bearing as to why manufacturers want the plugs gapped at this measurement. I would not have thought that .002" - .003" would make any difference but it did. So it turned out the brand did not matter (for this test) but gapping the plug properly did, it can and will make a difference, after the results were in.
