why won't my caliper bleed?

here's one i couldn't figure out.

a few years ago my C4 vette got a front c6 z51(13.4") brake swap done to it. i never could get the driver's side caliper bled. every time i cracked the bleeder, either with foot pressure on the pedal or with my motive pressure bleeder, it let out a steady stream of bubble filled fluid. i went through this several times and when the car had an electrical gremlin right after our son was born i parked it.

fast forward to yesterday i got off my butt, got motivated, and tracked down and repaired the gremlin. we also went to summit racing and picked up a small truckload of parts to replace the things i'd been borrowing off of it for the last couple years. i forgot how nice it sounded, and now i'm itchy to get it past the emission nazi sniffer test(only 2 more before it's old enough to be exempt) and plated.

i removed the big brakes and put all new stock parts back on, because the more i thought about things the more i didn't like the adapter brackets i had to modify to work because they were not machined right. but it still bugs me. why wouldn't that caliper bleed? there were zero fluid leaks, and everything bled perfect with my stock calipers back on.

it's all moot, just figured i'd throw it out there to see if anybody had any bright ideas.

Not properly drilled bleeder orifice? Manufacturing defect that would make the bleeder hole smaller than it should. Small hole + large pressure = turbulent flow = lots of bubbles in fluid.

That's all I could think of.

I had some calipers that would not bleed, but there was no air coming out just clean fluid. The calipers were new and some bubbles were sticking inside the caliper. hitting them with a plastic hammer brought the bubbles up and allowed them to be bled.

If a caliper is installed on the wrong side, the bleeder will be at the bottom and it will be impossible to bleed.

Dont know that it could apply...but in the MG world people put the calipers on the wrong side every so often; this puts the blleder below the hose input. Air only goes uphill.

Upside down caliper.

Very small leak in the line somewhere. Put a bunch of pressure on the pedal, like stand on it. Then inspect every junction for a slight wetness.