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Charlie K wrote:
I had several (three to be exact) when over 500 hours,
that I
would discover a mag drop that traced to a individual plug which had
a
cracked insulator. No other indications anywhere of
detonation/mechanical/dropped plugs during its history. Can it be that
the
porcelain becomes more brittle or soft or??? Any ideas??
During my General Motors Engineering days,
broken plugs were an issue. Tests were run and we found most mechanics over
torqued spark plugs and that plugs that were spec'd to be torqued to 19 ft lbs
would fracture the electrode when torqued to 29 ft lbs. When the electrode
fractures, the plug is junk and also it is a lot easier to break the
ceramic if the electode is fractured. Since then, I always use a torque wrench
to install plugs.
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