| Author |
Message |
Mitch Alsup (Mitch_alsup)
Member
Username: Mitch_alsup
Post Number: 877
Registered: 4-2002
| | Posted on Monday, July 14, 2003 - 10:29 am: | |
"What might cause the gap in a spark plug to widen ?"
The gap widens as each spark erodes a tiny piece of the electrode. Exotic metals (platinum) just slow down the erosion rate. After billions of sparks, enough metal has been removed that the gap is measureably wider. |
John Millard (Jmillard308)
New member
Username: Jmillard308
Post Number: 34
Registered: 5-2003
| | Posted on Sunday, July 13, 2003 - 9:07 pm: | |
Bill
The centre electrode degrades - increasing the gap - could cause a misfire, but unlikely at the gap you mentioned - sounds like it was something else wrong with the plugs.
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Bill V (Doc)
Member
Username: Doc
Post Number: 380
Registered: 9-2001
| | Posted on Sunday, July 13, 2003 - 8:24 pm: | |
What might cause the gap in a spark plug to widen ? The reason i ask is that my '85 308 began to misfire a bit a couple of days ago and I inspected the plugs/ extenders ( both with only about 6k miles on them) . The only anomaly I found was that one plug had a measured gap of about .039". I gapped these plugs ( NGK 6's) at about .028 and installed them myself about 6k miles ago and inspected them about 1k miles ago. So, the gap widened by about .010" by itself. I replaced all of the plugs and the problem totally cleared. So far, I've put about 250 miles on the new plugs and it 's running flawlessly. By the way , all of the plugs looked very good. The one with the widened gap was somewhat richer-burning looking, but not outrageous.
First of all, what would cause this gap change and , secondly, would this difference cause a misfire? |
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