Move Statamic's word based truncation to a modifier, it will also close any open tags in the generated excerpt. Copy the folder word_truncate folder to your _add_ons folder. Apply like any other filter with a colon to indicate the number of words you'd like in the excerpt.
{{ content|word_truncate:75 }}
That will produce an excerpt 75 words in length.
You can change your ending with a second parameter
{{ content|word_truncate:75:more }}
However be careful as it's likely to trigger issues if you put much more than a text string in. If you need something more then edit this bit of code at the top of the plugin
if(isset($parameters[1]) && $parameters[1] != "") $ending = $parameters[1]; else $ending = "…";
Replace … with your preferred ending.