weird m/c problem

[LMDGUY]

I have done a few disc brake conversions and replaced m/c and have never seen this happen. Im working on a 67 Lemans installing a conversion kit from: http://www.performancesuspension.com/ its the "silver kit" real basic . Everything bolted up fine , followed directions step by step, made new brake lines nothing leaks.. We went to bleed the system, started on the right rear (got sum fluid out) then the left rear (same as right) when I got up to check the level of fluid in the m/c , fluid was shooting out of the front bowl?!?! even after we had stopped pumpin the pedel it was like a little fountain spraying fluid , high enough to hit the hood? what the hell causes this? is the m/c bad. Any info will be help full.