Fuel Injection vs. Webers, what's the difference in plumbing/hardware between the 2 Options

[Type 47]

OK, i get carbs only need one fuel line, but hey, there are 2 sticking out of the bottom of the tank.

I Did the Tangerine SS lines to eventually go back to FI, but going with the Webers to get the thing up and running.

Out of the tunnel and into engine bay, what's going on with the orphan fuel line? Block it off out of the tank or in the engine bay? Which one gets blocked off? The one with the tank screen filter or the other?

And What the Hell is this little white tube? Is it for the FI or does it have some function with the carbs? I don't think so but I keep seeing this tube in my disassembly pics.

[Robarabian]

The one with the filter is the supply line. Do not block it off. Even with carbs you can and should run the return line. Weber makes a fitting for the dual carb setup that is a "T" banjo. You plumb supply to one side of it and run the other side to the return line. That way the fuel is being cooled and you wont vapor lock.

I assume you know you cant use the stock fuel pump, you need 3-5 psi, not 60.

IF you're not running the return line, then yes, you can cap it at the tank, not the line end, which would be real dangerous.

[BK911]

The one with the filter is the supply line. Do not block it off. Even with carbs you can and should run the return line. Weber makes a fitting for the dual carb setup that is a "T" banjo. You plumb supply to one side of it and run the other side to the return line. That way the fuel is being cooled and you wont vapor lock.

I assume you know you cant use the stock fuel pump, you need 3-5 psi, not 60.

IF you're not running the return line, then yes, you can cap it at the tank, not the line end, which would be real dangerous.

Just for clarification...
The pump does not produce 60 psi unless the system is designed that way.
With a supply and return line, the pump will not make anywhere 60 unless there are restrictions somewhere in the line.
The PMO fuel regulator is perfect for converting from FI to carbs.
With a stock pump, adjust the return pressure drop until the pressure hits ~4 psi.

[Superhawk996]

The PMO fuel regulator is perfect for converting from FI to carbs.
With a stock pump, adjust the return pressure drop until the pressure hits ~4 psi.

Generally speaking, it is bad practice to use a high pressure fuel pump intended for fuel injection to feed carbs.

Makes no sense to use a pump capable of 30 psi to feed 3 psi to carbs.

Pumping fuel up to high pressure and then regulating it down just adds extra heat to the fuel. There is a reason Porsche used a different low pressure fuel pump for the /6 carb equipped cars.

Then there is an added failure mode with a high pressure FI fuel pump. If the pressure regulator fails, you'll have high pressure fuel at the carbs which will completely overwhelm the float and flood the carb fuel bowls. Far better to have a low pressure (~5 psi pump) that is regulated to 3 psi. Then if the regulator fails, car will still run (but poorly).

[BK911]

Generally speaking, it is bad practice to use a high pressure fuel pump intended for fuel injection to feed carbs.

Makes no sense to use a pump capable of 30 psi to feed 3 psi to carbs.

Pumping fuel up to high pressure and then regulating it down just adds extra heat to the fuel. There is a reason Porsche used a different low pressure fuel pump for the /6 carb equipped cars.

Then there is an added failure mode with a high pressure FI fuel pump. If the pressure regulator fails, you'll have high pressure fuel at the carbs which will completely overwhelm the float and flood the carb fuel bowls. Far better to have a low pressure (~5 psi pump) that is regulated to 3 psi. Then if the regulator fails, car will still run (but poorly).

Sorry, not trying to argue, but I think it is important for others to understand the system.

Paragraph 1 and 2, no comment.

Paragraph 3: The pump does not produce high pressure, it only produces what it needs based on the pressure drop of the system. If there is no pressure drop, as in the pump is open ended, there will be next to zero pressure in the system. As you adjust the regulator, it imposes a restriction on the return side that increases the fuel pressure. You add just enough pressure drop for your desired psi.

Paragraph 4: PMO regulator is a mechanical regulator with a bolt that adds pressure drop to the system. It will not fail.

So in the diagram below, crank down on the regulator until pressure is set where you want it at the carbs. If the regulator is wide open, there will be very little overall pressure in the system. As you start cranking the regulator closed, it will increase the system pressure BEFORE the regulator.
The old school pressure regulators are crap and add the restriction before the carbs. For that type of regulator I completely agree with all your statements above.