rusty wrote:

New guy here with a question and looking for guidance!  I have a 1967 Mustang coupe i've been working on for a couple of years.  Original 289 car with factory disc/drum. I have rebuilt the front suspension, Cal tracs on rear.  Narrowed a 9", 31 spline Dutchman axles, 4:11 with spool for racing and 3:55 with detroit locker for cruising.  Built C4 wth upgraded valves/shift kit etc. I went a little overboard and built a 347 Stroker and have too much cam.....if thats possible!  Ended up with virtually no vacume for power brake booster.  Installed Wilwood 1" bore manual master cylinder and brake performance is  "poor" at best The pedal is hard as a rock!  Wilwood techs have been no help! Have rebuilt calipers,new pads etc.  Rear has new drums/shoes/wheel cylinders.  I read a threat here about resetting the proportioning valve (my dash brake light is on).  Will give this a try but looking to soften pedal before my right theigh gets so big I have to buy a larger pant size !   Any thoughts?  Can I continue to run origIinal design distribution block (formerly power assist brake) with the manual master cylinder?

Any help is greatly appreciated!
Rusty

 
Going to manual brakes from power is pretty much going backwards. If the vacuum is too low, you can get an electrically powered vacuum unit to run the booster, independently of the engine vacuum.

If you decide to remain with manual brakes, you will likely need to switch to a MC with a 15/16" bore. However, you'll need to get the pressure differential valve re-centered before the brakes are going to work properly. If after the valve is re-centered and the brakes don't work to your expectations, then try the 15/16" bore MC.

Other than a lack of vacuum, the biggest problem right now is the pressure differential valve being off center.

Last edited by ultrastang (8/12/2014 6:31 PM)