Re: Space between new prop and gear case
Don't know of any prop that sits back from the gearbox. You have to have a thrust washer as that is what you "thrust" against when the prop pushes thru the water.
Sitting back from the gearbox would be like porting holes used for better hole shot. At low rpm's the prop's blades would be flooded with exhaust gasses (much more than you get with the porting; might not even get your boat on plane.
Some props requre a different washer. I've been shopping props again lately and some will specify that this prop or that one "requires thrust washer part number xyz".
You don't have it on backwards, do you? I know Merc only goes on one way. Guess Johnny does too?
Mark