we installed a disc kit from matts on my 66 ss. bleed everything, but still can't get a pedal. it's adjusted out the whole way at the pedal/ clevis. still when brakes are applied they go to the floor before you feel any pressure. no leaks, no air in the system, and pretty much no brakes. took it out for a test drive today and when i first hit them i thought i was going to roll out into traffic. had to adjust the rod out the whole way ( last couple of threads)just to get the brake lights to stay off. any input on this? just got the car together,and really wanted to drive it to my daughters wedding next week. i emailed matt,but guess i'll have to wait till monday for a response. this is a 9 inch booster/master setup. grovey

check the rod from the booster to master i had to add some l to the rod in side of the car as well

I did a disc swap last fall. I had problems with a soft pedal too. I could see the calipers working.It turn out I had to bleed the back brakes better. It took a while but now the pedal is great. At first there was nothing coming out of the rear bleeders.That is what I would check first. Have someone open the bleeder at the rear and make sure you have solod fluid coming out. The rear brakes are what give you the pedal feel.

brakes have been bleed . i bench bleed the master. gravity bleed the whole car. then bleed the whole car three times. i think that making the rod longer would help it. i want to see what matt has to say about it, maybe he's seen it before. when i bought he said he sells 30 kits a day ! my bet is the longer rod is needed or a bad booster.

make sure caliper are installed with bleeders facing up !!

If you keep the engine off and pump the brakes what happens?
Once the vacuum is gone you should have a hard pedal-if you don't then you aren't pushing on anything.
If you have a hard pedal from the beginning then you probably have some more bleeding to do. How about the proportioning valve? If the piston shifted over you won't be able to bleed the rears properly.

Check the back of the mc where the rod goes in, it maybe too deep(wrong master cylinder).It happened to me on a disc conversion kit.