fuel return line questions

[slowerthantime]

I am about to install fuel lines. My planned set up to feed the L20B is stock fuel tank, inline filter, Carter 4070 pump, Holley fuel pressure regulator to 2 x DCOE 45s. Fuel lines 3/8 copper/nickel line. I was going to install and cap off a return line for possible future use but after reading through a bunch of posts, it seems there is merit in running a fuel return line with this set up (vapour lock, fuel pump load/ temps etc).

Is it worth running the return line?

I assume the return line would need some restriction to maintain line pressure? If so, what size should I use?

Cheers!

[bertvorgon]

Funny, I was reading through my log book yesterday and noted my restriction in my return line. Many years ago I re-checked the "pill" size which is up in the trunk, right before the fuel drops back into the tank, on my return line.

So.... .035" is the size I use on my Weber.

I would try that,watch that the fuel pressure stays ok and go from there.

The return line does help with vapour lock and makes sure there is always some flow so the pump does not dead head.

[slowerthantime]

Thanks Keith.

[bertvorgon]

I'm thinking that in late spring, on a nice clear break in the weather, with my NEW headlights in, that one of my first drives will be up to see your car. The Hope Princeton is a blast when there is no traffic, I had such a good run when I went to the Peach Festival car show.

I have a few customers that were mine that live in Summerland.

[slowerthantime]

The bbq will be ready.

I can't find much for an off the shelf in-line restrictor. The Sea-Doo guys seem to use a barbed connector with one end tapped to accept a Mikuni jet.


There is a Cobra guy who makes an aftermarket return kine kit. He makes a restrictor by tapping an AN fitting to hold a set screw that has a suitable hole drilled in it.


Then there are oil restrictors for turbo applications


Out of this lot, I'm leaning to the AN/ set screw set up for ease of changing restrictor sizes when setting the system up. Does anyone have other options?

[bertvorgon]

I just took a simple double barb fitting, soldered one end...WHAMMO...restrictor pill. It was quick and dirty at the time.

That "pill" has been in use since I perfected my fuel system back in the 70's, thanks to Ak Millar in California.

[zKars]

Could even use a needle valve to tweek the orfice in real time to get the pressure just right.

These are pretty affordable. https://www.mcmaster.com/needle-valves
Even have locking handles to keep your final setting.