Just finished restoring this Elgin 128 11j Sn 5515417, how ever since i do not have an Elgin Catalogue I do not have a clue which case it should be going into.I have tried it in a few cases that I do have, but was not able to adjust the time on it to see if it is running fast or slow. If some one whom has such knowledge and would like to inform me please i would be grateful to know. thanks Francis.

If you're not aware of it, this site is very helpful for Elgin collectors:
http://elginwatches.org/help/serial_number_info.html

It tells us your watch was made in 1894, it's a 16 size, open face, and pendant set.

Almost any standard 16 size case should fit. There is a threaded sleeve in the stem of the case that can be adjusted so the keyless work of your movement will properly shift from wind to set mode. Often, this has to be adjusted when a watch is re-cased.

I would choose a case with a raised stem similar to the following:
http://www.auctiva.com/hostedi...rmats=0,0,0&format=0
or:
http://www.auctiva.com/hostedi...rmats=0,0,0&format=0

Cases without the raised winding stem are a later style. A round winding button looks particularly nineteenth century. A proper case could be gold or silver in color with a smooth or engraved surface. It should not have a hinged metal cover over the dial.

When shopping for a case, pay attention to the location of the mounting screws and/or mounting screw marks. If you can find one where the marks match your mounting screws, your watch will have a more original look.

I would watch E-bay. See if you can find a non-running 16s parts watch with a nice open face case. This is usually more cost effective than buying just the case plus you can usually see from the pictures how the mounting screw locations compare to yours.

Be patient. Be choosey. Make sure the case back is not dented and that the back and bezel thread or hinge properly. I wouldn't worry about the condition of the crystal, though. A new White's Crystal (he's a member of this forum) will, for very little money, make your watch look like a million.

Sounds like a nice project. Please let us know how it works out.