Need brake system help - feels like wooden brake pads

[davepl]

This is actually in my '69 Impala but the braking system is pretty much the same as my truck, so though I'd ask here.

I have had a problem - slow to react brakes - for years ever since I first put rear disc on. I've long since taken those off, and now the system is a complete Willwood setup, but the problem remains!

Here's the problem:

The brake system does not respond quickly enough for panic braking. Although the system is able to provide full lockup it takes a couple of seconds for braking force to build.

Another way to describe it would be that the pads feel like they're made out of wood and don't bite/grab the pad at first. We've tried several different pad types (organic, metal, semi), and it seems not related.

It feels as though the brake fluid is being forced to operate through a very small orifice, so that it takes time but ultimately has the full force.

Last time the car responded properly was factory drum-drum.

I then upgraded to factory front disc and mid-80s rear disc, with Corvette master, and that’s when this all began.

Ultimately the entire braking system from the pedal forward was replaced with Willwood, and the problem remains! So the only parts that remain from the problematic system are the pedal, the pedal box, and the pushrod.

The brake pedal rides about equally high as the clutch pedal, so I don’t think it’s wildly out of adjustment. But could a maladjustment of the brake clevis, and hence the brake rod angle, cause any of this?

Any other ideas that don’t involve lines, master, or the brake themselves?

Remember, new rotors, pads, mounts, lines, master. I've tried a hydraboost in place of the vacuum booster, same result (but then a but more assist once it gets going).