FYI if you haven’t pulled your spark plugs the gap will probably be way off. Pulled mine yesterday to clean at 74 hrs 2021 Caracal 225 4s all were in good shape. Motor ran as should but I’m sure some performance was lost. Here are my readings:
This is not an isolated issue. I know of several Mercury 4s owners with factory installed plugs with gap inconsistencies.
Spend the $100 and get a Mercury Service Manual from Mercury publications. Every aspect of your motor is in there it’s an invaluable tool.