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October 27, 2023 at 9:14 am
#282096
look up the engine model by serial # in marine.com to confirm the suggested plug type.
Mercury Marine Outboard Motor Parts by Engine Model (marineengine.com)
on the 7.5 I see some ser#s with conventional gap plugs yet my 1970’s little 4.0 hp uses surface gap plugs and runs all day long idling without a hickup.
https://maxrules.com/oldmercs/timing/55.pdf
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