my sunny truck runs factory booster and discs(fr), pedal feel is ecxellent.

pulls up harder than my old r32 turbo. Has gone better than -1g under brakes (simret brake tester).

Yep, i cannot say how modified brakes work. Only that stock 1200 disc brakes can have a firm pedal.

brake shoes adjusted and tight, just larger salve cyls in rear and 200 b brakes up front.

Or you could simply adjust your brake shoes. Stock Datsun 1200 has a high, tight pedal when they are properly adjusted. Need to adjust every six months to keep it tight.

pedal wont feel good with the booster but better than a small bore diameter master expleiing almost all its fluid with a long pedal travel like mine( if find it ok, its 3/4 to the floor, still bit longer than a stocker which was 1/2 way to floor)

I found moving up to 20mm rear slaves the biggest drama for my pedal travel and feel. keeping 17mm on rear and larger disks up front worked well, but fronts would lock before the rears, now more balance braking but slightly longer pedal travel. Stock twin master cyl

Too true,but now a curved ball....a larger diameter disc rotor will reduce pedal pressure,however increasing the rolling radius of the tyre has the opposite effect requiring a more vigours push to get the same result...all a balancing act in the end.
For the record,my cars do not use power brakes(but they have been tried)without good feel.

well i would say my brakes and yours are comparable nick (pigdog)..

the only difference you have a bigger master and a booster as well

so conclusion...

if you want to put a bigger master cylinder you will need a booster as well

so new question...

why bother with either???

I agree. My old man has a VF hardtop with a nasty 340 out of a class winning marathon boat. You have to pull down the trans into 2nd or 1st (It's an auto) if you want any kind vaccuum assistance from the booster.
Otherwise it's heavy as hell. (The pedal)

Pigdog
Have you run a vacuum comparison between a stock engine [almost any engine] & a cammy dual sidedraught equiped engine?

My little 1200 GX would pull 18" Hg at cruise & a fair bit more at idle [900rpm] which is quite enough to make a booster perform at its best.

The hot engine will develop adequate vacuum when the throttle is closed at speed but the vacuum signal decays significantly as the RPM & the road speed decline. Some hot engines are flat out making 5" Hg at idle although these would be seen more as race engines.

If the booster in your car provides a significant benefit then it should remain there as the vacuum signal must be adequate, but I wonder just how much better it would work with even more vacuum as you would get from a stocker.

As I had said, the Weber equiped Valiant Chargers didn't have brake boosters because of the low vacuum signal, so Chrysler used a different master cylinder to try & address the problem.

For what it's worth, a small bore master cylinder will provide more hydraulic pressure at a given measure of input [pedal] pressure, but will have longer pedal travel in order to displace the required volume of brake fluid.
In order to get an unboosted system to work properly, the pedal travel may end up being excessive.

A larger bore cylinder will displace a greater volume of fluid for a given measure of pedal travel, but will generate less hydraulic pressure for the same input [pedal] pressure.
With this system the pedal travel can be brought back to acceptable limits but the pedal pressure required to provide adequate braking may end up being excessive.

It's all a matter of balance between the two.

all you people with small brakes picking on me all the time

my point or points were more that a worked carby motor can make a booster work fine and that its more the master cylinder bore size rather than the car size that determines whether or not you need a booster