getting new prop tight enough

[benwa43]

I took the prop back off and checked the key and the prop on the shaft without the key. Everything seemed ok so I dabbed on some anti-seize and tightened the nut as much as I possibly could. It is much tighter than before - now over 90 ft/lb but I still think I notice a vibration above 3400 RPM. I can feel it in the floorboard when sitting in the driver seat. I don't THINK there was any vibration before this incident.

[M3Fan]

I went to tighten my prop nut and there is simply NWIH I could possibly tighten it to the next notch on the castle nut. No way. I just tightened it as much as I could while still being able to sneak the cotter pin by the castle nut. It makes the nut more snug, but I'm sure it will loosen again in time. The nylock may be the way to go.