soldering 4 ga copper wire?

[treed2 at wsu.edu (T. Reed)]

So I'm redoing my grounds.. and this time I'm determined to solder instead
of crimp. Particularly after the no-starting fiasco I went through in
weeks past.

Any tips on how to go about this? Obviously my little 25w iron isn't going
to cut it. I'm afraid a propane torch will just burn off the insulation..

-Toby

Also I'm looking for a good ground point. My lower starter bolt has proven
to be a crappy one at best. I'd like to nab one of those A2
engine-to-tranny bolts that has the small stud protruding from the
bolt head designed specifically for this purpose, but the junkyards
around here are worth their weight in honduhs so I haven't had luck
finding one.