[Excaliber]

No gap or a VERY small gap? If it was a teeny tiny gap the plug and cylinder could still fire and it might take a couple of thousand miles to show up as 'fouled'. It's not uncommon for plugs to be dropped at some point during manufactur or shipping or installation and the side electrode gets 'bent'. LOTS of times plugs are installed without really LOOKING at the gap as they come out of the box. You might check one or two and determine there 'good to go' right out of the box, but you missed the ONE damaged plug! I've seen this happen a number of times over the years and now I visually inspect every plug.