diff --git a/src/calibre/ebooks/conversion/preprocess.py b/src/calibre/ebooks/conversion/preprocess.py
index ca74b04e8d..7f27d7a465 100644
--- a/src/calibre/ebooks/conversion/preprocess.py
+++ b/src/calibre/ebooks/conversion/preprocess.py
@@ -353,7 +353,7 @@ class HTMLPreProcessor(object):
                   (re.compile(r'((?<=</a>)\s*file:////?[A-Z].*<br>|file:////?[A-Z].*<br>(?=\s*<hr>))', re.IGNORECASE), lambda match: ''),
 
                   # Center separator lines
-                  (re.compile(u'<br>\s*(?P<break>([*#•]+\s*)+)\s*<br>'), lambda match: '<p>\n<p style="text-align:center">' + match.group(1) + '</p>'),
+                  (re.compile(u'<br>\s*(?P<break>([*#•✦]+\s*)+)\s*<br>'), lambda match: '<p>\n<p style="text-align:center">' + match.group(1) + '</p>'),
 
                   # Remove page links
                   (re.compile(r'<a name=\d+></a>', re.IGNORECASE), lambda match: ''),
@@ -567,6 +567,7 @@ class HTMLPreProcessor(object):
         html = html.replace(stop, '-->')
         # convert ellipsis to entities to prevent wrapping
         html = re.sub('(?u)(?<=\w)\s?(\.\s?){2}\.', '&hellip;', html)
-        # nbsp gets changed to space: html = re.sub('(?u)(?<=\w)\s(\.\s?){2}\.', '&nbsp;&hellip;', html)
+        # convert double dashes to em-dash
+        html = re.sub('\s--\s', u'\u2014', html)
         return substitute_entites(html)
 
diff --git a/src/calibre/ebooks/conversion/utils.py b/src/calibre/ebooks/conversion/utils.py
index 56c9c9673e..51f81978cf 100644
--- a/src/calibre/ebooks/conversion/utils.py
+++ b/src/calibre/ebooks/conversion/utils.py
@@ -156,9 +156,9 @@ class PreProcessor(object):
             [r"[^'\"]?(Introduction|Synopsis|Acknowledgements|Chapter|Kapitel|Epilogue|Volume\s|Prologue|Book\s|Part\s|Dedication)\s*([\d\w-]+\:?\s*){0,4}", True, "Searching for common Chapter Headings"],
             [r"[^'\"]?(\d+(\.|:)|CHAPTER)\s*([\dA-Z\-\'\"#,]+\s*){0,7}\s*", True, "Searching for numeric chapter headings"],  # Numeric Chapters
             [r"([A-Z]\s+){3,}\s*([\d\w-]+\s*){0,3}\s*", True, "Searching for letter spaced headings"],  # Spaced Lettering
-            [r"[^'\"]?(\d+|CHAPTER)\s*([\dA-Z\-\'\"\?!#,]+\s*){0,7}\s*", True, "Searching for simple numeric chapter headings"],  # Numeric Chapters, no dot or colon
             [r"<b[^>]*>\s*(<span[^>]*>)?\s*(?!([*#•]+\s*)+)(\s*(?=[\w#\-*\s]+<)([\w#-*]+\s*){1,5}\s*)(</span>)?\s*</b>", True, "Searching for emphasized lines"], # Emphasized lines
             [r"[^'\"]?(\d+\.?\s+([\d\w-]+\:?\'?-?\s?){0,5})\s*", True, "Searching for numeric chapters with titles"], # Numeric Titles
+            [r"[^'\"]?(\d+|CHAPTER)\s*([\dA-Z\-\'\"\?!#,]+\s*){0,7}\s*", True, "Searching for simple numeric chapter headings"],  # Numeric Chapters, no dot or colon
             [r"\s*[^'\"]?([A-Z#]+(\s|-){0,3}){1,5}\s*", False, "Searching for chapters with Uppercase Characters" ] # Uppercase Chapters
             ]