What BBLADES said. ^^^^^. 55lbs nope!!!. The nut will loosen. 2x4 in between cav plate and prop 65- 75ft lbs , i like 75 with a little grease. Check it after an outing then again after few more. Especially on new props and hubs. Its a 3/4 nut you wont hurt it.
yeah old thread i know. I have had bolts loosen a couple times on different boats, now they get tightened. Last year one guy lost a prop another guy, bolt came loose. Both of them torqued to 55. Didnt want hear my story.

It's not what I say it is what Mercury says. I typically over tighten too. (without even realizing it.)
But, with a new fiberlock nut, 55 lbs. is fine.

Brett

I set the torque wrench at 65 and use a touch of blue locktite as well. Let it set overnight and good to go. Never lost one yet. Have seen a set take the deep dive, not mine, at the Merc clean 55 and good to go. That marina employee adjusted his procedure on the bosses boat to 75 and red!