I popped the hood and discovered a small crack in my revhard cast mani. It looks to be about the size of a pinhole, but I want to know if this is a huge deal.

I currently need the car to drive about 20 miles (10 there, 10 back) this weekend, and don't have the time to take it to get welded.

Anybody know if this is treacherous, or what? I've got no clue.