New to the forum and I was wondering if anyone could help shed light on some of my issues. I am currently converting an automatic 73 Grande to manual, I have a set of manual pedals and have noticed that the brake pedal stud for the manual assembly is much higher making me think that manual brakes are required which seems a little silly so, I was wondering if there is perhaps a booster specific for manual 71-73s. Also, I am unable to find where the clutch cable/linkage would go through the fire wall I tried to look for a punchout or some significant dimple to signify where to cut a hole but, was unsuccessful. Any help would be greatly appreciated Thank you.
The location of the linkage exit will surprise you. The punchout is actually in the steering column firewall bracket, where the column passes through the firewall. There is a replacement grommet piece available from parts vendors that have the correct grommet for your linkage to exit.
As far as the pin height on the brake pedal, I had the same problem. The pin height for the manual setup was about 1.5 inches off. I believe that the difference is the manual setup you have is from a manual brake car. Most automatic cars had power brakes, and I believe that the manual cars were more prominently non-power brakes. Since I could be wrong with that, let me help you fix your problem, which is what you really want.
There are 2 simple fixes.
1) Use your original brake pedal and cut the pad area of the pedal to a manual size. THis won't be perfect, but it works. Just put the shorter pedal tread on the trimmed metal pad, and most people won't notice. I did this on my car years ago.
2) Take your original brake pedal and your 4-speed brake pedal to a weld shop and have them switch the metal pads over. You could have them move the pin on the pedal, but that is a riskier move. If you move the pad and for some reason the weld fails you still have the ability to brake and stop the car. If a poor or defective weld is done on the pin and that weld fails your ability to stop the car is gone. Also, the stresses on the pin weld are greater than those of the pad weld as the pin sees shear forces that act across the plane of the weld. The pad sees compressive loads in a complimentary direction to the weld, greatly reducing the likelihood of load induced failure.
Hope that helps. Build a fun car, but never compromise the factory safety features!