stuffing box size?

[bhstech]

My Cat 27 #6298 is on the hard for the winter and I have several projects I want to do in the spring. One is to replace the, probably, 30 year old stuffing box packing. I remove the nut, out of the water of course, measure the shaft (1") and getting the inside of the nut proves difficult. The major Dia. of the external thread is 1.5". So the leave the difference as 1/4 packing. However, 1.5, or somewhat less, is the root dia of the internal thread.
The minor dia of the nut is going to be @ 1.4 assuming a 12 pitch thread. I can't actually measure the pitch but is appears to be unf. Standard course thread for 1.5 thread is 6 and there are definitely more threads per inch than 6. So 1/4 (.25) packing may be too tight. 3/16 (. 1875) seems a bit loose. I've search around the interweb forums and some boats seem to have 1/4 and other 3/16. So, will 3/16 expand enough to fill the void?

[Blue Stocking]

A 2 inch Brad with a 1/2" bent 90* and a pair of vice grips will hook it out in no time flat. 1/4" packing compressed a little flatter will go in easily and squeeze out as necessary. Wrap at least 4 times around the shaft tightly, and cut along the shaft in line with the start end. Stagger the joints evenly when loading into the nut.

[shakey doug]

Try hammering the 1/4'' packing thinner to obtain the thickness needed.

[Stu Jackson]

KISS

Buy both, find what fits, return the other.