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#16539
BRIAN MARSHALL
Participant

I’ve heard that the problem is caused by the porcelain insulator no longer being glazed, but can’t really confirm that. If I were you I would try the repro KLG ML50 plugs from the Green Spark Plug Company. They are a longer reach than the NGK 18mm plugs so you MUST put an 18mm tap down the plug holes to clear any carbon build up from the innermost threads, before trying to install them. The full story is that these plugs are being made at the behest of the Bugatti Owners’ Club, who were desperate for long-reach 18mm plugs. When Kenelm Lee Guinness died his KLG plugs were made by Smiths Industries, but in recent years the long-reach plugs went out of production. Tim Green was able to acquire the tooling and commission a batch to be made. Other benefits of these plugs are that they give an increase in compression, and no Japanese trade marks !