What is going to happen when I remove the master cylinder?

Syleng1 said
Just to add here for somebody that may not know the difference.
Disk /drum master cylinder has one resivour larger than the other. Larger is disk requires more fluid than the drum 1/2.

Drum/ drum master the resivour s are the same size as the wheel cylinders are typically needing close to the same amount of fluid. Also I learned because brake fluid gets hot and disks get even hotter. The extra fluid is also a basic type radiator. Also the larger qty of fluid is a safety margin if you lost brakes you have so many stops before you ran out of brake fluid.
Technically the proportioning valve has a valve that detect the lack of pressure from the leak and shuts down that pressure.

It’s not so complicated. Do more reading thru the search as a lot of conversions have been discussed on this board about this matter. Education is only a “click”away. Good luck.
Joe

The metering block is what detects low pressure the proportioning valve restricts pressure to the rear wheels so they don't lock up in a disc brake application which is why it's only used in disc brake cars from the factory.some people add them to dial in their brakes too and you can even get aftermarket adjustable ones . Drum brake cars all have metering blocks . With the disc brakes you may only have a proportioning valve so you need to research this But the block that the feed lines from the master to the front and rear lines on a drum brake system is a metering block which is why it has a fitting for the idiot light wire on it.Basically it's a ground switch that makes contact when you lose pressure in either side of the block making the light come on.