Fuel lines and twin carbs Options

[JFG]

I am fitting twin IDF 40's to my 1.7 engine (it came as a rolling shell) and need to change the fuel lines from front to back.

Do I need to install a return line?

What size outside and\or internal diameter are the standard lines?

I'm going to make my own using stainless steel and need the specs to buy the correct pipes.

Finally. Do I need to tap a vacuum take off into the manifolds for the distributor?

[Dave_Darling]

Some pumps do not require a return line. Some do. So it depends entirely on your choice of fuel pumps. If everything is apart, I recommend installing the return line regardless. If you don't need it, you can cap it off or just ignore it. Much easier to do that than to install the line after half the car is together.

The supply line is ~9mm OD. The return line is ~7mm OD.

Far, far easier to get the lines pre-bent from Tangerine Racing.

Tapping the carbs for vacuum advance is not necessary. It may help things, depending on how you set everything up, but it might not.

--DD