1959 25hp Elgin fuel mixture

Most motors of that time were running 16:1 or 24:1. I would start at 16:1 and if the plugs foul change to 24:1. Elgin was the Sears brand name motor before Gamefisher. If your model number begins with 574, which I suspect it does, then it was made by McCulloch. If it begins with 571 it was made by West Bend. 1959 was one of the years where Sears was changing makers to McCulloch but was still under contract to West Bend. West Bend made a 35HP, 12HP, 7.5HP, 5.5HP and 2HP motors. McCulloch made the 25HP, 40HP and 60HP motors for 59.