If helpful here is a 79 4sp l82 routing. Egr, air pump, and exhaust flapper preheat valve plugged
looks like brake hose also is supposed to be upright..
i took pics when carburetor rebuilt so i wouldn’t screw up.
your car looks pretty honest and original

 

It is not about "flow", it is about pressure. The booster needs a dedicated vacuum source to produce enough vacuum pressure to operate the brakes correctly. The PCV hose should not be tee'd into the booster line. The PCV system does have actual air flow. The brake booster line does not flow. You can use a vacuum guage reading on both hoses to verify that these systems have different vacuum levels.

 

Actually its both flow and pressure. When you release the brake pedal, un-metered air flows into the engine because the pressure is low in the intake manifold which drives the brake system flow. If there is some blockage, air can't flow, and the brake cannot develop a vacuum in the booster.

Pressure is a scalar, it has no direction. But air does not always flow from high pressure to low pressure - it flows from high energy to low energy (Bernoulli's & Energy equation).
HGL is the hydraulic grade line of the pumping system or static scalar pressure. EGL is the kinetic energy of velocity vector for flow. For example in a venturi pressure drops and then rises, the gas flows from low pressure to high pressure in order to exit the venturi. It will flow from low pressure to high pressure region this way.

We can write simply as Pressure + Kinetic energy + Z(negligible axis) = Total energy of a flow.

The pressure loss or drop inside a 3/8" Diameter hose due to the flow of the pcv system, is negligible with respect to the flow rate.

In other words, The 3/8" hose has the same pressure as the intake manifold at all times, with or without the PCV flow attached.
PCV flow does not change intake manifold pressure in a meaningful way.
Therefore, The brake system will not notice that there is any change with the PCV attached because it has negligible affect on intake manifold pressure.

If you'd like I am willing to setup an experiment and collect data to show this on a couple vehicles. I will use 1-bar map sensor to determine changes in pressure with and without PCV attached. Anybody? Bet?

 

I owe it to you guys and to all automotive forums which seem to perpetuate this myth purely based on consensus. A consensus is meaningless.
100 scientists got together and wrote a book about why Einstein was wrong , a consensus of a hundred scientists are wrong, it is meaningless, as Einstein was right and his math was his argument.

It doesn't matter what you think or what people say. What matters is the argument, the math.
Here is my argument in mathematical terms. If you have some argument to counter, it must be done using math or evidence as Data. It doesn't matter what you think or anybody else thinks. That is an enormous problem on forums, people share information and reach consensus among themselves, it is meaningless. Do the math. Collect Data if possible. THEN make argument validity.

First here is the properties of the air and the Hose being used for PCV / Braking. It is a 2Foot hose in this example, with 3/8" inside diameter. Typical automotive hose.
The air density at atmospheric pressure is around 1.225kg/m^3 however when the intake manifold is at 15"Hg~ The pressure is around 7 or 8psi and the air density is around half. That is typical idle and cruise vacuum applied to the PCV system. The atmosheric pressure is a worst case scenario for wide open throttle, there is no vacuum and the brakes would not work but still lets just see what the pressure drop would be under these bad-as-possible condition.

We will evaluate the change in pressure using Darcy-Weisbach equation


Typical Automotive PCV systems flow 1 to 3CFM. I calculated this already a while back for the fixed orifice 0.1"Diameter on a Corvette for example, this is the equation I am using

https://www.corvetteforum.com/forums...post1605229916


Here are the results with atmospheric pressure and intake manifold vacuum.


'PSI Change' Is the change in pressure due to the flow rate in CFM.
Notice it takes around 20CFM of flow, which is about ten times what the typical automotive PCV system flows, to exert a change of 1PSI in pressure inside the hose, when intake pressure is about 8psi (idle/cruise typical pressure).

Even if we placed 5PCV valves in a 'T' fitting with the brake booster, the change in pressure is only about 1/4 of a psi.

I conclude that PCV flow is negligible with respect to braking performance and that is why I've done it for decades and will continue to do so.
Is it wise to isolate the brake booster hose? Sure why not. But if its not convenient to do so - it really doesn't matter in terms of pressure even with multiple PCV valves tied to the same hose as I have and continue to do so, some engines need 3x pcv valves to evacuate their crankcase. The PCV system is a tuned system, if you change something on the engine like the intake pressure or air filter, the PCV system needs to be re-evaluated.

I am willing to accept and evaluate any counter arguments based on math or evidence such as empirical data collected from an actual vehicle.
Otherwise, A consensus is not evidence, it doesn't matter what you say, just words, people copy an idea and paste it somewhere else. That isn't proof of anything other than human stupidity.

 

Here you can see my equation and online calculators agreement as I checked my work for each step
In other words, I did the math myself, then checked against a few online calculators to make sure the numbers lines up. Since, I will Rarely edit posts, so I am extremely cautious posting numbers.