brake problem

[nvrdone]

So here's the story:
I have a'49 3100 that I am trying to convert to power brakes. I installed a braket kit from CPP with the recomended Mustang master cylinder & booster. I also installed the 1/2 " extension to the pedal linkage. I am using the stock pedal with the under cab mounting along with the stock 11" drums front & rear. I did install a 10 # check valve in the m/c since the m/c is for a disc / drum combo.
Now the problem. The pedal goes down about 4" before the brakes engage. Ive got the brakes adjusted to a slight drag, the system has been vaccume bled etc.
I'm at a loss to solve this problem. Any ideas ????
Thanks.

[mknittle]

dose it do it with the engine off? if so I could be the pushrod in the booster is too short.

[Russell Ashley]

My first thought is that you need a m/c for drum brakes. There is very little fluid movement in a disc brake system since there is so little movement of the brake piston. Using a disc m/c with drums where there is more fluid movement might be causing your low pedal.

[OrrieG]

Russ is right, you need a drum/drum MC, fluid dynamics between disc and drum brakes are much different.

[itstheshu]

I had to adjust the pushrod between the master cylinder and the booster all the way out to get mine to work.