Torque value for spanner nut?

[Country Dirt Kid]

What I have here is a spanner nut that presses the prop shaft along with the reverse gear into the gear box. The spanner nut is marred from the last person who owned the engine. It looks like the removed it by using the punch method. I'm currently trying to find the right tool to reassemble. I want to know if there is a torque value for this thing? It has to be fully seated or else the reverse gear wont engage with the dog clutch. Any ideas? Thanks for the help! The motor is a 1980-81 Mercury 20 hp.

 

[Country Dirt Kid]

Here is a better question. I should have asked this first. Does anyone know the name of the tool used to tighten this nut? I know that it can be done with a punch but as you can see someone already marred it with a punch. I took this nut to Northern Tool and they just shook their heads. Any Ideas? Thanks

 

[minuteman62-64]

Don't know if this will be of any help - but, on my 1982 30 HP Mariner it is called a "Cover Nut" and is installed and removed with a "Cover Nut" tool. My manual shows a torque spec of 60-75 ft. lbs. for my Mariner.

In the absence of a model specific torque spec, it appears that "pretty tight" would be the operative criteria

 

[jimmbo]

100 ft pounds is the spec for a 1980 20hp. Cover Nut tool is the name used in the service manuals