EFI conversion fuel lines

[furious70]

My fury has been using the oem style fuel and vapor return lines with efi for 11 years no issues. Vapor line is the original one.

 

[72RoadrunnerGTX]

Just did that conversion on one of my '72s;
https://www.forbbodiesonly.com/moparforum/threads/sniper-hyperspark-install.192294/#post-911552305

 

[USatC]

Just did that conversion on one of my '72s;
https://www.forbbodiesonly.com/moparforum/threads/sniper-hyperspark-install.192294/#post-911552305

How does the efi run compared to a carb (besides the easy starts)?

 

[72RoadrunnerGTX]

How does the efi run compared to a carb (besides the easy starts)?

What, perfect startups, hot or cold, not enough? For me, next best impression would be the overall throttle response improvement, even when cold, no warm-up time needed. As others have mentioned, the Sniper sequential throttle shaft linkage makes for a bit of a touchy off-idle throttle response, got use to it pretty quickly however.

 

[70chall440]

Unlike some, I saw "F" SS braided, hate that crap. I have used a lot of it and have the scars on my fingers to prove it. On my Cuda I went with Fragola 8000 series nylon braided and have never looked back. I use push lock fittings which work exceptionally well. That said, I generally run hard line from the tank to the engine compartment (Nicop, steel, etc.) and then use Fragola to go from the hard lines to the tank or to the regulator/fuel rails.

I will tell you right now that quality tools are pretty much mandatory. You can get by sometimes with cheaper stuff but you want good flare tools and good tubing benders. You can run soft/flexible line the full length of the vehicle and to be honest if you protect it you will be fine.

 

[451Mopar]

The nickel copper is easy to work with.
3/8" supply and return is common in most applications, but a 5/16" return should work fine. The 1/4" vapor return line might work depending on the fuel pump size. I haven't tested with a return line that small.
The '69 Coronet is using the Spectra EFI fuel tank. It has a 3/8" supply, and 5/16" return connections. Uses a Walbro pump, I think 250 LPM?
I did a few FiTech regulator tesst on the '71 Charger with the Fi-Tech 380 LPH pump and a Walbro 450 LPH pump. The regulator had no problem keeping the pressure down to the correct pressure, and the regulator orifice is pretty small.
The FiTech can also pulse with modulate (PWM) the fuel pump when there is low fuel demand, so the 1/4" return might be doable?

 

[Wietse]

I used 3/8" aluminium fuel tube, easy to bend and could go in 1 piece.
Was easier than expected to get it in place, just make the bends slowly bit by bit and you can get it around all places you want.
At the tank and engine compartment i went with a teflon hose with SS braided sleeve and on top of that has a rubber coating.

Below is from a local manufacturer here in NL, but Summit will have similar products.
https://www.qspproducts.nl/en/qgtub...-4M-Aluminum-tube-4-meter-9-5-mm-qsp-products

https://www.qspproducts.nl/en/qgssp...hose-SS-braided-PTFE-D06-coating-qsp-products

Fittings and adapters are crush type, pressure rating will be a fair bit higher than required but keep it as a safety margin.
All area's near the headers and exhaust are covered with a heat protective sleeve.

 

[INTMD8]

The FiTech can also pulse with modulate (PWM) the fuel pump when there is low fuel demand, so the 1/4" return might be doable?

I ran a 1/4 return line next to the 5/16 feed on my twin turbo 70 Malibu and had no problems. Used a Walbro 255 pump and a boost a pump.

 

[threewood]

Holley recommends at least 3/8" feed and return line size with their Sniper EFI.

 

[INTMD8]

Seems they do, but it's not needed.

If you wanted to test if the return line is large enough, loop the feed line to the return with no regulator, run the pump and measure system pressure (if there is any). That's 100% re-circulation and minimum possible pressure.

If that is less than what your base fuel pressure will be, a larger return line will do nothing.