This procedure continues to be debated.
I have always loosened, then tightened, but recently we was told by an
assembly chief at Pratt & Whitney that they don't loosen--they tighten
the nut as they find it. Some say that as the gasket has already
compressed a bit, that the loosening then tightening is not needed. P&W
engines are worth a couple of million bucks as they go out the factory
door, but I don't suppose they are working with chunks of cast iron as we
are....
Bob
On Mon, 14 May 2007 09:52:53 -0700 Dave and Liz DuBois
<ddubois@sinclair.net> writes:
> > Some engine builders recommend backing off the nut slightly and
> then
> > bringing it back to torque specs.
>
>
> This is an important step as it take a lot more torque to get a nut
> that
> has been tiightened in place moving than it takes to keep it moving.
>
> Thus, loosening and then torquing to spec by having the nut moving
> as it
> comes up to the required spec is a much more accurate method of
> gettint
> it at the correct torque.
>
> Cheers,
> Dave
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