So in doing a Weber swap from Zenith carbs there is an issue with the Webers not having a fuel return line. There is no set up for that on the Weber carb.
I think I may have come up with a solution...
Out there in the world exists a fuel line restrictor which can help with this, I think. One end of it has a small hole to allow excess fuel to dribble back to a return line. It would go in-line somewhere in the mix but I am not exactly sure where.
I drew up this janky diagram to give you an idea of what I am thinking...



Can anyone say this is correct or have any better ideas?
thanks!

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1969 w108 280s

While the intent of the fuel return was to:
1) provide a variable fuel pressure in response to manifold pressure,
2) possibly provide slightly cooler fuel by recirculating a small amount back to tank,
the use of a fuel pressure regulator will provide the benefit of constant (and adjustable) fuel pressure without the need of going through a trial and error process to determine the "appropriate" return orifice size, a size that will yield the correct fuel pressure at only one combination of pump speed and engine demand. The Webers commonly operate at a fixed fuel pressure, usually in the 2-3 psi range.

That makes total sense.
I have a pressure regulator ready to put in line set at 2.5 when I get to plumbing it all together.

So with that do you suppose I should be ok without a return? I would like to avoid a possible vapor lock situation

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1969 w108 280s

Although there very well may be other makes that have used a fuel return with carburetors, as distinguished from fuel injection, it seems to be unique to MB.

Vapor "lock" occurs on the suction, low pressure, side of the fuel pump. A return line cannot cure that. You may safely cap off the return.

cool.
Done and done, Thanks Frank!

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1969 w108 280s