Well they are hard to get out and have a Loctite type of product on them you need to use heat . When I reinstall them I use two nuts back to back and Loctite stud lock. I tighten them as much as I can with a normal spanner.
I do not know if this is correct or not.
I do know that back in the day Race Teams would cut slots in the top of the studs so they could be unscrewed with a flat blade screwdriver. This enabled the top end to be taken off without taking the motor out of the frame.This gives me a clue that the studs were not super tight.