Correct prop torque

[denpat]

I have a 1991 Mercury 8 hp that I have removed the prop to grease the shaft and check for fishing line etc. The prop nut is a nylon lock nut without a cotter pin or tabs to lock the nut. Clymers manual says to tighten the nut to 70 inch pounds. I did this and it doesn't seem like it is tight enough. The Clymer books says 150 inch pounds for a 4 and 5 hp, 70 inch pounds for a 8 to 15 hp and 120 inch pounds for a 20 and 25 hp. Does any one have any other specs or does the 70 inch pounds sound about right.

[staylor]

I've had several 15s and the 70 in-lb did indeed feel like it was not enough- so I tried adding more on one motor and ended up stripping the nut. I then measured the thread, which was metric if I recall, and obtained some plated steel elastic stop nuts and washers. I installed the washer and then the nut and torqued until the rubber hub was flexing- probably about 150 in-lbs. I also saw a 15 at a dealers with a nice bronze elastic stop nut- so maybe this is also available. I note that I never had any trouble with the plastic nut loosening- but I just didn't trust it.
Doug

[beeman]

Ok my corolla front wheel bearings i tighten that nut 130pounds was hard as heck with bar mind you. I put my new lock nut around 50 to 70 pounds, on outboard. 150 seems extreme high.

[Hot Runr Guy]

Ok my corolla front wheel bearings i tighten that nut 130pounds was hard as heck with bar mind you. I put my new lock nut around 50 to 70 pounds, on outboard. 150 seems extreme high.


150 INCH pounds Brad, not FOOT pounds!
HRG

[Burr]

70 inch lbs, about 5-6 ft lbs. I don't know if you could overcome the effect of the nyloc on the nut with 5-6 ft lbs. I'm in the camp that says it doesn't sound adequate. You can do what you'd like, but I'd just snug it up and call it good.