After putting in a new engine this winter, I had trouble with the
engine misfiring at low idle on no.s 1 and 3. When it was dark one night
I noticed that the spark was jumping ffom the bent plastic insulator at
the end of the wire over to the heater pipe. If I twirled the plasic
elbow away from the pipe, it jumped about 1/2-3/4 of an inch to the
head. I couldn't figure out why the spark should want to jump that gap
rather than the one inside the chamber, and I couldn't fathom why it
should only happen at low idle. The plugs in question were champions
that were from my old engine, but had very little miles on them. I
replaced them with new NGK's and everything works great. I still don't
know what was wrong. Perhaps they were too oil fouled from my last
engine and not getting a good ground. Maybe they were bad plugs. I just
know I'll be using NGKs from now on.
Michael Hering '67 TR4A IRS
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