Over the years I've read various opinions of upgrading the 10hp Mercury/Mariner to a 15. On occasions folks have been convinced it's just a matter of changing jets or similar. As I have both engines here at the moment it's the first chance I've had for a proper comparison.
The 10hp carb image is the one with the obviously reduced throat size so confirms a whole replacement carb would be needed.
I used to get this enquiry a lot when I was working, and to get the answer I used to check the carb if they were the same check the jets, check the cyl block p/ns are the the same , and the same with the crankshaft and pistons and conrods, and dont forget the propeller. That was one of the interesting parts of my work before I retired.
