Big cam dual fuel line

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Dino soar, Oct 12, 2018.

  1. Dino soar

    Dino soar Road Train Member

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    I'm going to install the dual fuel line on my Cummins big Cam and I have a few questions.

    1) is a return line needed on the front head or is the return line on the back head sufficient?

    2) do I use the original size that runs to the back head and just copy that to the front? Or are all the fuel lines lines to be made larger?

    3) I have seen some that look like they use braided line instead of the steel line. Is there any reason or benefit for this?

    4) I read somewhere about using a larger line that feeds the pump and using dual filters. Does anyone know sizes or part numbers?
     
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  3. SmokinCAT

    SmokinCAT Road Train Member

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    Only one return is needed.

    Use at least 5/16" line to match the factory setup, whatever you ed up with do not go smaller, the volume through the line is just as important as pressure.
     
  4. SheepDog

    SheepDog Road Train Member

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    A picture of the completed set up would be nice, ,anyone?
     
  5. 062

    062 Road Train Member

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    If you ask real nice maybe @OLDSKOOLERnWV will snap a pic for you.
     
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  6. Working2party

    Working2party Medium Load Member

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    The reason you’ve seen kits with a steel braided line is because it’s an SOB to map and get the bends right to clear everything and look presentable when it’s finished. Especially above the fuel pump. If you take your time steel line is the most cost efficient route and what I used on the 2 trucks I added the duel lines to. A flexible line would have saved a lot of headache and “readjustments”, but anything that will flex can bulg or swell and could act like an accumulator and add a delay in throttle response. I’ve never used a steel braided line in this application, so I can only imagine how good or bad it would work.
     
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  7. OLDSKOOLERnWV

    OLDSKOOLERnWV Captain Redbeard

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    As mentioned earlier factory size line is all that's needed. My front line is the same as the rear, with a "Tee" in the top of the pump to hook both lines. Originally my front 90 degree fitting and line was a rear line from another engine with slight alterations.
     
  8. OLDSKOOLERnWV

    OLDSKOOLERnWV Captain Redbeard

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    Yes a flexible line will alter response, not that's it's extremely noticeable but you can feel the line expand.... I tried it and didn't like it. I'm fortunate to have some good freinds at the local hydraulic shop, having other lines built with stainless braid is not a problem, just not fuel.
     
  9. OLDSKOOLERnWV

    OLDSKOOLERnWV Captain Redbeard

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    Looking at the lines on a N14 can give some good Mental blueprints as well.
     
  10. ODR

    ODR Light Load Member

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    I did this to my big cam years ago. I didn't notice much of increase in performance but sure did smooth out the idle.
     
  11. Dino soar

    Dino soar Road Train Member

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    Did you guys have any problems getting the plug out of the front head?
     
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