the studs should go in hand tight and then backed off half a turn, and the nuts should go on hand tight and then cranked down a full turn. if it's not sealing, crank it down another half a turn
torque measurements are fairly useless, clamping force is what you're really looking for. torque ratings can be skewed by things like rust or dirt in the threads, damage to the threads, an overly tight or loose fit between the male and female parts of the threads. basically anything that's not a perfectly clean, new, lubricated and in-tolerance bolt will give you skewed readings.