If nobody hits on this I'll tell you what I do. When I buy something new it seems to be torqued to the published spec that the bolt/nut can handle without ripping the threads out or snapping off. I even had an oil filter on my Generac standby generator fail at the seam because it was torqued too tight.
There are numerous places on the www where you can pull up torque specs based upon materials, dimensions, threads, wet or dry and all that. The only time I use a torque wrench is for head bolts to ensure that I get even distribution. Otherwise I use common sense in analyzing the application, size and material, wet or dry, and what feels right.
I use a pneumatic impact wrench (have several sizes in 3/8-3/4" drives) and I watch the twisting action of the socket. It will run down fast then upon making contact, it will slow until it finally stops. Once stopped I let it whack 3 or 4 times and stop....a flywheel nut may get 5 or 6 whacks.
On smaller hardware, wrenches are smaller and that helps you to control your hand pressure. I always use an X pattern on plates and wide surfaces with multiple hardware and make 2 or 3 passes before final snug. If I am worried about it not being tight enough, I may get out a 4 oz. hammer and give the end of the wrench a couple of whacks after I have put the final hand pressure on the wrench.
Over the years, I haven't broken a bolt since working on a Henry J head back in the early '60's and never had something leak or come loose. The last time I stripped a thread was back in the 50's (teaching myself to be a mechanic) stripping out a spark plug on a 1955 Scott Atwater 10 hp outboard...never did that again..... On spark plugs, with a new gasket, I finger tighten, wrench down feeling the gasket compress and when it is fully compressed and I feel the resistance rise, moderate whoopie on the wrench and that's that.
On aluminum outboards, corrosion is usually a problem and especially on the engine block, its easy to break bolts. I find a good penetrating oil helps and I use impact over brute force to back out stubborn bolts...impact defined as the wrench and the 4 oz hammer, and back and forth motion till it breaks loose and you can back it out by hand. Once out and ready to reassemble, run a tap in the block to clean out the threads and use a thread locker...I prefer blue since I never know when I will be back.
Hope this helps. Had nothing else to do this AM, being 17 years retired and had nothing else to do besides trying to help folks.
