Classic/Antique Car Repair: 79 Corvette brake pedal, corvette brake, calipers

Question
My brake pedal is very soft when engine is on, the pedal is normal when engine is off, all brake parts are brand new, no leaks any where, I bled the brakes 10 times still no luck, can you please guide me what to do ?
                       Thanks

Answer
Check the calipers and make sure that you have not put the left side on the right side and visa versa, they will fit. But what happens when the caliper is on the wrong side the bleeder screw is on the bottom rather than the top. When the bleeder screw is on the bottom it is impossible to get all the air out of the system. Let me know and id this is not it we will go on from there.
Brad