[Henry Schmidt]

Our experience is that what ever the factory uses it's very strong.
I believe a low strength thread locker will work but in truth we use 574. I seems to seal and is for easier to work with if for some reason you must remove the fitting.
So many of our engines are for racing purposes that we need to be able to disassemble them with relative ease.

I have never seen a torque spec on that fitting but I would speculate about 24 ft/lb.
Remember that the quality of the aluminum sealing ring may dictate the maximum amount of torque this fitting will take in this application.