Is it possible that by not having a fuel return line installed on a carburetor equipped car, the motor would run excessively rich? I don't see how it would be possible, but i just read this recently. The reason that I'm asking is because my motor in my car is running extremely rich and I have taken everything apart and cleaned everything up in both carburetors numerous times and nothing seems to fix the issue. The motor is a brand new 528 hemi with two edelbrock 600's on it. I have a fuel pressure regulator installed and set it at 5 psi, so there's not too much pressure pushing past the needle and seat. I installed the lightest step up springs in the carburetors to help hold down the metering rods at idle. I don't have any vapor locking issues. I'm at a loss at this point of what the problem is and that's why I was even considering this as a possibility. I don't see how this would fix it, but I'm willing to try adding one at this point.