I have a 17.5 sea nymph aluminum runabout with a 1978 Johnson 85hp manual tilt. I am running a 17p stainless prop it has had carbs rebuilt ,new tanks, new lines new coils, new powerpacks,new fuel pump . compression is 120 on all cylinders.It cruises at 3400 24 mph and top speed is 33 at 4200...