Did you have brakes before you changed the lines? You may simply have air trapped in the master cyl? Instead of pumping the brakes try this. Go to the right rear and open the bleeder screw. Get someone to push the pedal to the floor and hold it. Then tighten the bleeder back up and have them release the pedal. Do this 3 times for each wheel starting with the right rear then left rear then right front then left front. This will help to push any trapped air away from the cyl. After this if you still have a low pedal then try to bleed them normally. JB...Make sure you check the fluid level from time to time wile you are bleeding the system so it don't run out of fluid.