Everything is new except the metal lines - I converted from drums to discs so it has new calipers, hoses, mc, booster and prop valve. I would suspect the metal line if only one wheel were sticking, but both makes me think MC or prop valve. I called up firebird central (which is where I got the mc, booster and prop valve) to see if maybe they sent me the wrong (drum/drum) prop valve and they don't even carry a drum/drum setup, so doubtful. It's really odd, and if everything wasn't new I'd start from the wheels and work my way back but I feel like it's up stream from that...

First I would work the pedal a little bit , then break loose a bleeder on a caliper and see if fluid shoots out.
It should just dribble at the most.
See if the lines are holding pressurized fluid that way.

If you pass that test -

I'd take a caliper loose and artificially simulate the thickness needed to fill the gap from piston to the housing.
Leave about 1/4" gap for movement.
Have someone press the pedal and release while you watch the piston move and retract.
Then do again with 1/2" gap and see if any improvement in retracting.

New Chinese calipers could be flawed or defective or junk.
fwiw

Problems like this usually involve the caliper or the caliper hose.
Your new hoses should be okay

I did some more testing and the brakes seem to hold for a second or two before releasing. I didn't take it for a drive but they are not dragging or holding at all when I test the brakes parked. I was able to notice them taking a second or two to release by driving on a sloped area of my driveway, if I let off the brakes, the car wouldn't start rolling for a second or so and then you could feel the brakes release. They may just need to be bedded in, or it may be something funky in the m/c not retracting properly. Could low vacuum on the booster cause that potentially?

Booster problems usually give less effective brakes.

I had to block sand the pads with 40 grit to skinny them up , and then finish with 80 grit , to get to a point where my Dads calipers would retract properly.

Had to do that trial and error process twice to get satisfaction.
But saw improvement the first time - and continued the process.
And was using a slide caliper (measuring tool - not car part) to measure before and after thicknesses.
Was taking about 1mm off each time.

For full disclosure I actually was re-using his old outer pads that still had some meat left.
Maybe half worn
So was only sanding down 2 of the new pads to use on the inner side against caliper where most of the wear occurs.
In your situation I would sand all 4 pads 1mm each for starters - then take any extra material needed off on just the outer pads.

Wear a dust mask if you do any sanding on pads.
His pads were ceramic carbon fiber and dulled the sandpaper within a minute or so.
Original thickness of pads including the metal backing plate was about 17mm

If you use a pry bar or big screwdriver to wedge some clearance in your pads to remove the caliper - the piston should try to protrude back out a little bit on its own from some of the back pressure still in the lines - if you leave it alone and observe.

If it doesn't do that , the piston is usually hanging in the bore.
Since yours are new they might not be properly finished all the way at the back of the bore.
Thinner pads will keep the piston more into the sweet spot - in a case like that.

If they are "new" Chinese , its likely that is a culprit.
If they are newly remanufactured GM calipers it would be less likely .

edit : the lip on the caliper piston seal aids in pulling the piston back when pressure lets off.
If the piston is hanging , it can't do that .

caliper seals play a part in retracting the caliper piston.
sticky pistons,hard seals will keep this from happening

Thanks for the pointers, I'll see what I can figure out. The reason I went with all new stuff is so I wouldn't have these issues, but I guess in today's world that's not any kind of guarantee.

I think it's the booster. I unplugged it and went to manual brakes and if they're dragging, it's vastly reduced. No more brake smell, wheels were warm after a quick 1-2 mile drive but not hot at all. Going to see if I can source a new booster locally and return the one I have, though it's 2.5 years old so unlikely.

Great to see it coming along!

I did some more testing on the brakes - definitely something in the booster/mc. If I leave the booster unhooked, brakes do not drag at all. I tried shortening the pushrod enough to where it's not even able to hit the brake switch and with the booster plugged in, the brakes drag. However, if I pull up on the pedal, they release. So it's like there's a return spring or something not quite strong enough to push the pedal back only when the booster is plugged in. I do have the booster I pulled off of the car and it was working fine, so I may dig that out of my parts bin and swap them to see if It fixes the issue.

I did take the car for a spin and everything else is working and the 400 is pulling strongly.

https://photos.app.goo.gl/HZbyJsLRA3Hkuy7o7

Had a flashback.
About 10-12 years ago worked on a 89 VW Jetta with dragging front disc brakes.
It was the booster.
Had to put washers between booster and master so he could keep driving it until a replacement booster arrived.
And they were sort of iffy in that arrangement.
Redneck compromise

Would definitely try the old booster since you have it on hand.

Old booster fixed the problem. I'm not sure if it's the booster or the insert into the mc to adapt it to the booster, but that insert wasn't needed with the old booster as the pushrod protruded into the mc properly. Installed and it works perfectly, just doesn't look as nice.

I sorted a few other small things and went for a ride, and found the alternator isn't charging. I think I'm going to see if I can source a one wire alternator instead of trying to figure out if it's the voltage regulator etc.

Talked to body guy and dropping it off later today, should be done by mid July!

Glad you got your booster issue figured out.

Got the alternator swapped with a 3 wire, super easy using this guide: http://www.wallaceracing.com/alt-conversion.html

Then took it for around a 20 mile drive and no major issues! Was good to drive it, that's the most it's been driven since 1991 when my uncle parked it. Then I promptly loaded it on my trailer and dropped it off at the body guys shop. Next pictures should be of it getting painted!

A couple of pics as body work starts.

Headlight assembly details
 

Could you share a few pictures of headlight assembly from yours?

How it all bolts the bumper and core support? Orientation of springs? I'm starting with bare plates and need to assemble from scratch and an Ames catalogue...

I wish there was an assembly manual. Camaro next time. OK, not.

Thanks,

Mike

Here's the other pic I took when I was reassembling, it's currently at the body shop but it's fresh enough in my mind that I can probably help if you have further questions.

Basically assemble to the point shown, then put the bumper and grills on together, keeping everything loose enough to move, then align as best you can before tightening it all down. The springs can only really go one way and you can use headlights to make sure you get the right buckets in the right place. If the headlights are not oriented correctly, you have the bucket in the wrong place. I forgot how the horns mounted so have one of them still off the car :).

I'm still not clear what the back part of the headlight assembly bolts to. I don't have three holes which align on the core support.

Does the outside bolt to a hole on the fender? You have the fenders installed in your picture.

Thank you for posting the picture and the offer to help.

They bolt to the curved horns that go from the frame to the upper header panel. See here:

https://images.app.goo.gl/N2w5Xg1Y8wGMRqkF9