318 will not start

friend had a brand new Edelbrock on a 390 Galaxy. Thing would not start, he called me and I went over, stuck my finger in the open power brake fitting on the back and said "You got a leak". The threaded allen plug was rolling around the bottom of the carb box. hand threaded it and it started right up. I bet you got a large leak, like your power brake hose is unplugged?