Need to clarify...
Not sure if you're replacing an engine or not. If your question is procedural, try this...Stuffing box best replaced on the hards, not in the waterREMOVALUnscrew thin brass jam nut to free up big oneUnscrew big brass nut completely.Spray WD-40 inside to loosen up flax.Turn corkscrew pick into first layer, pull Vise Grip offers better leverageRepeat until all layers removed 2 if was chinzy, 3 more likelyClear out brass seating of any loose debris so new flax sits wellINSTALLBuy 13 inches Teflon 1/4 inch to cut into three piecesCut the end at 45 degrees to dovetail with next cut, 45 degreesTurn first wrap tight, mark with blade (or do at home with 1-inch stanchion)Cut with share razor knife or Dremel sawCut remaining 2 wraps to same sizePoke first one in clockwise by turning big nut slowlyMark where it started with red penScrew down onto shaft to pack, by hand onlyLoosen and repeat two more timesDo not overtighten, or will burn flax and not seat properlyTESTWhen launch, be prepared to tighten using wrench keep jam nut looseShould be no drips at rest, do not overtightenIn gear, should be no more than 1-3 drops per minute preferably noneOptimum is no drips in gear “1-3 is an old wives tale,” says Fred at YardTighten one flat at a time while in gearIf the big nut is warm, back off as too tight burning the flax (unlikely)Always retighten the jam cleat to avoid inadvertent looseningWhen it’s right, try a day or week later takes time, be patientCheck again for three weeks then three months laterShould last three or four years okay to tighten one flat a time, over time