Torque wrench for prop?

[imported_airxsteel]

Do I need to use a torque wrench to put on a new prop for my 140 HP Johnson (1979)?

Not sure if I need to torque it down or can I just use a regular wrench and tighten it up .

I have heard different things and want to make sure I don't screw it up.

It has one of those castle nuts on it already, so I am thinking I don't have to, but was just wondering about it.

If I do use a torque wrench , how many pounds of torque would you use on it? 50 ? 60?

Thanks in advance.

 

[Texasmark]

Re: Torque wrench for prop?

I know that you don't want a loose prop on the propshaft. I know that my engine (Merc 90) is spec'd at 55 with the standard rubber hub. I also know that different props using plastic hubs require more up to a max of 100.

Best I can do.

Mark

 

[imported_airxsteel]

Re: Torque wrench for prop?

Thanks Mark.
I guess all I really need to do is make sure it fits the cotter pin and it should be ok. Hope so. d

 

[ziggy]

Re: Torque wrench for prop?

find out the torque value of that nut. and use a torque wrench. it's the proper thing to do. torque values are not just given for no reason. if you torque it down to the wrong value, you may find out that reason.. just tightining it up and hopeing for the best would get you buy in the field, when yer sol. but at the shop there are other options. use a torque wrench and do it proper with the proper information at hand. ie. the proper torque value of what ever your fastening per the oem. if ya don't have a torqe wrench, get one, they come in handy for many fastening applications. i find it surpriseing that many things i tighten don't require near as much tightening as i'd think when i use the proper torque value...
don't know about yer ob's but my I/O prop nut is torqued to 40 ft. lbs. + 5 up to the lock tab. i would dought that my torqure value is good for your ob either. someone else will have to answer with those facts for you....good luck with your fastening adventures........

 

[Texasmark]

Re: Torque wrench for prop?

Hey Ziggy, about your comment ...." find it surprising that many things I tighten don't require near as much tightening as I'd think ..." is amusing to me now.

You wouldn't believe the number of bolts I twisted off (and sparkplugs I stripped in alum ob's) when I was young and learning how to mechanic. I just thought everything had to be nutcrunching tight to work. Took awhile but I finally got the message. :%
Totally agree on how little it takes and the necessity of knowing where you are....torque wrench.

Mark