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Thread: Primer line options

  1. #1

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    Primer line options

    Thought I'd ask for opinions on replumbing the primer lines on my 0-320, has anyone used anything besides copper tubing? I've seen some flexible tubing that's rated for fuel but not sure if it would be wise, I've never seen anything other than copper used and suppose there is probably good reason but figured I'd see if anyone has had good results with any newer technology, any experimental guys have any ideas?

  2. #2
    Steve Pierce's Avatar
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    You can buy stainless lines to the cylinders. I use these AN800 ferrules on the copper. They are less prone to crack.


    Good thread here on primer lines. http://www.shortwingpipers.org/forum...t=primer+lines
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  3. #3

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    How about this question, do I really need a primer
    on my PA-18-180 ?

  4. #4

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    Primers

    I have a PA-18-180, do I need a primer ?
    Carb has accelerator pump ???

  5. #5
    Cub Builder's Avatar
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    For cold weather ops you're gonna want a primer. Pumping the throttle will shoot fuel up from the carb so it will start, but pumping the throttle won't keep it running. Winter starts without a primer will thoroughly exercise your battery and starter with multiple starts before the engine will continue running.

    I won't get into the possibility of fire from using the carb for priming, but I'm sure someone else will. Much better off to use the primer to shoot the fuel into the intake next to the intake valve.

    -CubBuilder

  6. #6
    Bill Rusk's Avatar
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    Might want to do a SC. Org search on this. A bunch of Alaska guys are doing just fine without a primer. You don't need one if you understand how the accelerator pump works. Just another opinion.



    Bill
    Very Blessed.

  7. #7
    Bugs66's Avatar
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    I used stainless instead of copper.

  8. #8
    aktango58's Avatar
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    Put them to all the cylinders also.

    Was in a 172 on a ferry flight, light freeze in canada and had to buy a torch and stove pipe to heat the engine to get it to run... and we tried and tried. Figured out it had one cylinder of prime.
    I don't know where you've been me lad, but I see you won first Prize!

  9. #9
    bearsnack
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    If my engine is properly preheated it starts without the primer. The only time I would need the primer is if I had a weak impulse coupling or something is giving me problems in my ignition system. I have been considering removing the whole system. Less weight, one less system to maintain.

  10. #10
    Bugs66's Avatar
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    If you are on floats on a lake and want to get it started quick (wind blowing, etc) , the primer is handy. If you need to hand prop, the primer is nice. How do you pump the throttle and hand prop at the same time? I'd keep it.

  11. #11
    jgerard's Avatar
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    As an IA I would question the removal of a primer system on a certified aircraft since it's considered a fuel system modification which is highly frowned upon with out approved data or a STC. If the primer is listed as an option on the TCDS and not part of the required equipment then it should be no issue to remove it.

    Regarding primer lines.... I prefer the factory Lycoming SS lines just like they show in the parts manual.

    Jason

  12. #12

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    Quote Originally Posted by bearsnack View Post
    If my engine is properly preheated it starts without the primer. The only time I would need the primer is if I had a weak impulse coupling or something is giving me problems in my ignition system. I have been considering removing the whole system. Less weight, one less system to maintain.
    BS, I have a great deal of respect for you so don't take this wrong. What is the definition of "properly preheated"? Lycoming recommends preheat when ambient temps are below 10*F (see pp49, para 2 of the link below). Does throttle pumping work well at that temp? It doesn't for me. So given that the engine manufacturer specifies it's appropriate to start an engine without preheat at 11*F, it stands to reason the primer system attached by the engine manufacturer should be operational. If an owner determines a higher preheat threshold to provide for warmer starting temps, like the widespread 32* value, perhaps the primer isn't as important. I don't think one answer fits all. I'm a fan of primers. Sometimes conditions don't allow for hours of pre-heat.

    I'm also a fan of occasionally preflighting the primer system. That is, pump the primer a few strokes and then physically inspect the primer lines for leakage. Otherwise you risk squirting raw fuel around inside the cowl right before startup. Probably a low risk of fire but I'm a little reluctant to allow fuel loose inside my engine compartment. And yes, I have found a primer line to be cracked and spraying fuel when primer was used (Lycoming, not TCM).

    http://www.lycoming.textron.com/supp...Operations.pdf

  13. #13
    bearsnack
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    My current 0-320 likes 1 pump of the throttle, crank (or hand prop) and it fires right off.
    I didn't see anything in the type certificate about primers. I think the only place you could get bound legally is if it is mentioned in CAR3 the certification basis requirements. Let me know what you find, Jason

  14. #14
    bearsnack
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    I am a little overboard on my preheat standards. If it is colder than 30 degrees above zero I preheat. If I am desperate I may push that to 20 degrees.
    I preflight them often , also. A broken line means an intake leak.

  15. #15

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    Everyone's viewpoints make sense. None are universal. For my part I use little Odyssey batteries. While they work great they don't provide tons of spin time so I want my engine to light as quickly as possible. In all conditions at initial start I can get a faster and more reliable start using primer. The colder it gets the truer that is but it still applies to 70* days. And we aren't going to see any more of those for a while.

    Good hunting, guys.

  16. #16
    supilot's Avatar
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    Quote Originally Posted by Steve Pierce View Post
    You can buy stainless lines to the cylinders. I use these AN800 ferrules on the copper. They are less prone to crack.


    Good thread here on primer lines. http://www.shortwingpipers.org/forum...t=primer+lines
    How do you crimp or press the AN800 fitting?

  17. #17
    supilot's Avatar
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    Where is the best place to buy a stainless/copper system pre-fabbed firewall forward for an O-320 or is that not really an option?

    Thanks

  18. #18
    Gordon Misch's Avatar
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    Quote Originally Posted by supilot View Post
    How do you crimp or press the AN800 fitting?
    Solder it. Clean and flux carefully, then pressure test with soap bubbles - it's a pain to fix a small leak once installed. Don't ask how I know that!!
    Gordon

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  19. #19
    Gordon Misch's Avatar
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    Quote Originally Posted by supilot View Post
    Where is the best place to buy a stainless/copper system pre-fabbed firewall forward for an O-320 or is that not really an option?

    Thanks
    It's easy to put together yourself. The 1/8" copper line and compression sleeves are available at Ace Hardware or Spruce.
    Gordon

    N4328M KTDO
    My SPOT: tinyurl.com/N4328M (case sensitive)

  20. #20
    supilot's Avatar
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    Thanks geezer

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