Can anybody remnd me of the substitute for the really old (really big) Chamion C7 spark plugs that were standard for a lot of the motors from the 20s and 30s? I want to say Champion D9 or D16 but I don’t recall specifics. Been dealing mostly with 50s era motors for many years now but am trying to get spark in a 1938 Thor with a Bosch magneto.
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