| ^^^ The 2 above posts are right on the money. I've spent a bit of time with my brake system and tried various 'experiments.'
What I've concluded is that the brake booster is a bit small and hence the pedal effort is a bit hard. What can be done? Well there's a few things. I replaced the BMC with a 15/16". What this did was give a definite improvement in how lightly I can push the pedal and get the brake effect I was looking for.
The only problem with this is, the pedal will travel a bit more than I was used to. I didn't totally like this. I mean the pedal can lock up the tires easily (EBC rotor, EBC Yellow Stuff pads, SS brake lines, rebuilt calipers, and Wilwood brake fluid).
I just still didn't like the low pedal height though. Another thing that can be done is a larger brake booster. This would be VERY HARD to do of course and require a lot of research and rework of the mounting system already in place. An easier solution would be to keep the 1" bore BMC (don't ever use the 17/16" as they call it, which is actually a 1 1/16" bore) master cylinder. This will make the pedal like rock! You don't want that. Anyway, as I was saying, you can use the 15/16" BMC and add in a brake booster vacuum pump. Race cars use this when they run big cams and don't get enough vacuum to run the booster.
A vacuum pump will pull more vacuum than the engine and hence, increase the power that the booster can supply. I've been researching this a bit and may go this route myself. I measured my engine vacuum at idle and I get about 16 in/hg at 5280' above sea level (Colorado). With a vacuum pump that could pull just over 20", I should be able to add power to the booster that would make my pedal feel more responsive without having to push harder like now with my current 1" BMC. Here's a link to one type of booster vacuum pump on the market;
https://www.mpbrakes.com/accessories/silent-drive-vacuum-pump-ac9001k.asp
This caught my eye due to its 'silent' operation. Some vacuum pumps are really noisy and you may not like when they kick on and rumble as they vacuum down the booster system. Also............. very important,,,,,,,,,,,,,, you would definitely want a vac pump that can supply MORE vac than the engine can supply. If you're at sea level and are getting say 17" of vacuum, and purchase a pump that can pull 17"-18", then you aren't going to gain much in the way of more power at the booster. So there you have it. Want more power with less pedal 'push,' then you can;
1) put in a smaller BMC and deal with the lower pedal height when braking
2) put in a larger brake booster, and deal with all the fabrication work that goes with that custom install
3) put in a vacuum pump that would supply more vacuum to the booster than the engine delivers, and therefore give more 'power' to the booster. Vinnie Vinnie
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07:38:58 09/19/17
