NGK spark plugs breaking.
Hi All: I seem to have a persistent problem with the plugs in my slant six 1974 Duster. The engine is all original and unmodified. As per recommendations on this forum, I've been running NGK ZFR-5N plugs, washers removed, gapped to .035 and torqued to 30 ftlbs. as per the FSM. I'm generally pretty happy with them, but have had three with broken electrodes lately. Has this happened to you? Any ideas why? Would you recommend a different plug? I'm a bit hesitant to move to another plug, but these keep breaking. Thanks - cruiser
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