A friend and I have just checked his plugs and have noticed that they have opened up considerably since they were installed less than a year ago. They were initially gapped at 0.7mm are now well over 1mm.

What would be the cause of this ? We also noticed that the original plugs that were replaced also had a considerable gap as well.


[Edited by Father Xmas - 21/06/2003 03:22:43]

 

When the plug fires, the arc is hot enough to vaporise a very small amount of metal from the tip.
Over time, this loss of metal widens the gap.
I tend to get a gap increase of about 0.2mm in 10,000 miles which leads to poor idling & performance and also crunchy gear changes(why??).
Regapping every 7,500 and getting new plugs every 15,000 miles seems to cure these probs.

Nick