I'm not sure, in all honesty. The JFBCFan module used to tolerate smaller widths. However, Facebook has always had a note on the widget page that the minimum size is 292px. We never enforced that because Facebook didn't. It looks now though like Facebook may be ignoring width settings that are smaller than 292px and using that value instead. You can see their documentation below and possibly test some different values and settings:
https://developers.facebook.com/docs/re … /like-box/
Sorry for the trouble. Hadn't noticed that they were enforcing this lately. The slimmer Fan module did have some graphical issues of text and images wrapping sometimes, and Facebook may have simply wanted a standard, good, look across any sites that use it.
I hope that helps, even if it's not really what you were looking to hear.