I hae been using green Loctite 680 for years on ALL the bolts and screws...The strongest is 638 green, but hard to find...Green 680 is more common and almost as strong...Either green is stronger than the other colors...
3W uses some form of Loctite on the threads of the prop stud..It takes my Mapp gas torch to get it hot enough to remove with a 3/8 air wrench...
You won't hurt the case of an engine by heating it to loosen any Loctite, even the Green..I do it all the time, 3W engines use it on the bearings in the case...
If you put green Loctite on the brass 4-40 screws holding the carb discs in place they will twist off before the green Loctite releases..I use a small butane torch or soldering iron to heat the screw first...Way better than losing a cylinder and piston if the screw goes through the carb....
You can Google Loctite and see all the different types and properties..