I am new to this site, I have owned my cougar for about 10 years now. It’s a 1967 standard cougar. It used to have a 289, 4 speed top loader with hydraulic clutch setup. It was a great daily but I wanted to go fast! I replaced the motor with a 408 and an auto C4 Tranny. I went with a rather large camshaft that did not build enough vacuum for my power brake setup so I removed the brake booster and replaced it with a Dorman M73323 master cylinder. Replaced the brake pedal and master cylinder rod with the correct one for manual brakes (disc all around). I bled all four and when I took it out to test they are HORRIBLE! I have to push the brake pedal with all my might just to get it to slow down from a 20mph roll. It feels like there is pressure but it just does not stop! Any idea? I did not change the proportioning valve, can that have something to do with it? I’m going to try and bleed all 4 corners again as soon as I have time; I have a 2 year old running around and time is very limited! Any and all comments are greatly appreciated.
Put the power brakes back on, convert your headlights to electric and use the vacuum reservoir to supplement your brake booster. My 408 only makes 10 inches of vacuum and this has worked well for me.
Too late for all of that, I already changed out everything to manual which I have no problem with. It’s going to be a 1/4 mile car. I have driven manual brake cars and they work great but I know something is wrong with my setup just can’t figure it out. But great idea on the electric setup for the headlights. I’ll be looking into that for sure, thanks!
Are you sure you put in a “manual” pedal support/pedal? IIRC the manual pedal arm mounts higher up to give more leverage on the master cylinder. You should not have to change the proportioning valve as it’s primary purpose is to control the balance between the front and back.
Also look at the bore size of the master cylinder - the larger the bore, the more fluid you are pushing and the higher the pedal effort. A smaller bore will reduce pedal effort, but if it’s too small you won’t be able to move enough fluid to lock up.
I went to the Dorman web site and they listed both the manual and the power bake master as 1in bore, I thought that the manual was 7/8in bore, and also pretty sure that the power brake peddle is the one that mounts higher in the bracket , at least that’s how it was on my 67.
I am positive that I have the correct pedal as shown on Steve’s site. However, I am not positive about the MC that I listed as when I purchased the unit was several years ago and only until recent was it installed, no box to reference anything my damn dog tore it up. Let alone I don’t remember where I purchased it from. But one thing i’m positive on is it was for a 74 Maverick with disc up front and drum in the back. I will look into a manual brake dist. block as noted above. Thank you to all for your input. I will update soon as I make the changes, may not be soon… Time is extremely limited right now.
So long story short, I found the front caliper was clogged for some reason. I opened the bleeder valve and nothing. Completely removed it and still no flow. So I left it off and pushed on the brakes which in turn built enough pressure to clear whatever was blocking the brake fluid. All is well now. Thank you to everyone for your help.