I have an 86 Elky that I just finished installing 12 LS1 brakes and I will be putting on rear disks very soon. The original Master cylinder will not handle the the LS1 cailpers and goes all the way to the floor. Does anyone know of a proven Master Cylinder that will handle this system, is a bolt in and will work with the original power booster?
Thanks,
Redryder

Are you sure that's the problem or do you think there could be air hidden in the lines?

I bleed them several times. Used a quart of fluid. I didn't see any more bubbles. I don' think it is air. The pedal is firm, but just has too much travel to give a warm tummy feeling when appling the brakes.
Redryder

I haven't run the numbers yet, but I also suspect that the master is too small to displace the fluid required to make all those pistons work.
I'm getting ready to do the same swap.
If I find out something I'll post it.

Baer recommends using the stock master cylinder with their stuff (which is basically LS1 and C5 parts).

I believe it, but my pedal is not as responsive as I'd like it to be, so it's either the master or the booster.
Maybe one of the two is bad.
Guess I'll have to diagnose the stock system first.......