o you keep getting air when you bleed it? try pinching hoses with vise grips one at a time to see if pedal stiffens.

How are your calipers mounted? Horizontal or vertical?

Call me in 5 min

440-225-9063 Brad

I'm running sentra calipers as well with a stock master cyl, dual handle CNC's and had similar problems with mine last year. We gravity bled it first, then used vacuum to get it pretty close but you still had to push pedal down twice to have brakes. I bought a 2lb residual pressure valve and put in and rebled it and worked like a charm. Might give it a shot?

Another little trick if your trying to bleed by yourself is to put a short length of vacuum hose on the bleeders and put some brake fluid in a jar, put the hose in the jar. Instead of pulling in air when you release the peddle it will pull in fluid. Eventually you will bleed all the air out.

I don't remember you saying whether you got a solid pedal and no brakes but it sounded like you have a pedal that can be pumped up but goes squishy soon after which says to me you have a leak(s). Sometimes fluid doesn't come out but there's enough room for air to be sucked back and forth through a joint.
I'm also betting you wasted money on that residual valve because you should be chasing a leak not throwing parts at it.
Granted I still had a stock system but it took me a couple years of rebleeding brakes before I finally solved my problem which was a combination of worn stock master and those PIA bubble flares VW uses.
I also think I increased the bore of the master because my dual master pedal was now pushing twice as much fluid. I also like the dual master because if one end goes dry you still have the other which is important when you're on the road like me. I almost bought a residual but those are more used to balance a brake system, like when your fronts are locking up before the rears start to grab.
good luck
I friggin hate brake pressure issues. That's why I had asked not too long ago in another thread about why no one was concerned about mixing and matching these different calipers and masters without concern for ratios. We do this in sportbiking but as you can imagine it's a bit more touchy and obvious when you've F'ed up your master ratio.

I almost bought a residual but those are more used to balance a brake system, like when your fronts are locking up before the rears start to grab.
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Pull the front end up on your trailer and then jack the front up some more so the master cylinder is the highest point, open the furthest bleed screw and let the air bleed out. You have air trapped in the system. The next question is did you bench bleed your master before installing it?