The Edelbrock swirl pot does require a return line.
https://edelbrock-instructions-v1.s3...rock/36031.pdf
However the written instructions (all without the need for a fuel return line) contradicting the the diagram instructions (5/16” FUEL LINE (NOT INCLUDED) MUST
BE ROUTED FROM THE SUMP OVERFLOW
VENT BACK TO THE FUEL TANK.)
Once again noted in item 10 & 11 in instructions.
Finally in the last section warning does it really spell out that the return line is a fuel vent line and not constant flow fuel return line it appears.
WARNING!
The fuel sump vent line is a critical part of the Fuel Sump installation. These instructions MUST be followed for safe
and proper system operation. A fuel rated hose must be routed from the vent port (see figure #4) back to the fuel
tank. The fuel tank must also be vented if not originally equipped with a vent line or vented cap. If the vehicle has
a vent line, you can tee into this line. If no existing vent line to the fuel tank exists, you must plumb a new line to a
point above the maximum fuel level of the tank (at the top) or in the fill neck. DO NOT run a vent line from the Fuel
Sump to OPEN AIR in the engine compartment or pointed to the ground. DO NOT run the vent line into any part of the
air intake system. Proper routing of the vent line is not an option. This procedure is mandatory for your safety.
Edelbrock is not responsible for any fires, personal injuries, property damage or any other issues pertaining to
improper vent line routing and or failure to follow these instructions.