Background: Basically changed entire car over last 2 years. New aftermarket 9" rear, built new k-member and added Lamb struts, added rack and pinion steering. Reason for drastic change was to support added power from roots blown smallblock. Car is 68 Barracuda Notchback.
Still using stock brake pedal assembly & rod. Only old tubing is from firewall back to proportioning valve in rear. Braided stainless line from valve to T on rear. New tubing from T to each caliper (Wilwood rear brakes).
In front everything new from MC to Lamb calipers. From rear MC port I have braided stainless to Roll Control and from the Roll Control to T. From T new hard line to each frame anchor point. Braided stainless from each anchor point to caliper.
I'm on my second MC with same results with each. I have bled these brakes at least 15 times using all methods I have access to. Vacuum, pump & hold, drip method and pushing fluid from caliper back to MC. The end result is the same. The first push on the pedal it goes to the floor. On second or third pump I get some acceptable pedal. After a few moments the pedal will again go to the floor but provide pedal after 2 or 3 pumps.
I've bled master cylinders alone more than once and I can separate systems to MC, front system and rear system and each individual system will hold solid vacuum.
I'm at a loss and any recommendations are appreciated. I have another new MC to try but I don't really think it is a MC problem, altho my son believes it is.