Prop Hub Size Difference

[jonathanr]

Hey Guys. Had to get a new lower unit for my Mercury XR4 some time back and had to end up getting one that has a bit higher gear ratio than the old one. Needless to say, I believe the hub size of props may have changed as well. I have a couple of 4" hub size props that I wanted to test out, but I noticed a small gap around where the prop actually meets the lower unit. The props fit onto the shaft fine with no problem. I wanted to play around with the props as they range in different pitch size and see if could the right one set up. The prop on the boat now is a Laser II and it has a hub size of 4 1/4" and there is no noticeable gap where the prop meets the lower unit. Can I run the 4" hub size with the gap or am I left to try and trade my other props for a larger hub size one? Didn't think about that when I got the lower unit. Thanks.

[Bob Smith (Porko)]

As long as the shaft size and thrust washer fit you should be ok. Sometimes the smaller outer hub size will allow for more exhaust gasses on the holeshot. That normally means more "blowout" on the flatter pitches, but could be useful on the higher pitches.