Primus 981 madness

Discussion in 'Fettling Forum' started by Alex74, Jul 5, 2020.

  1. David Shouksmith

    David Shouksmith United Kingdom Founder Member

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    Yes, I meant to say after my black oxide bit - so more likely above the burner than below. You got it sorted, though and that's the main thing. :D

    It was early, which makes a change from my usual excuse - 'it was late'... :oops:
     
  2. Nils Stephenson

    Nils Stephenson Founder Member

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    @Henrik
    The "silvery washer" is aluminium and it should have a fibre washer under it. Fibre is used there so it doesn't damage the enamel.
     
  3. Alex74

    Alex74 United Kingdom Subscriber

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    Henrik,

    I have a very similar washer under the same nut, so I bet that’s where it goes!

    Nils,

    Back to the fettling table and I just did what you have suggested. Sliding a new needle up the jet by hand, there is a ‘step’ or little obstruction in the new jet but not the old jet. I can’t quite shine a light inside them to take a closer look. I have also made a more robust ( less Heath Robinson) threaded coupler which enabled me to adjust the overall rob length to 154.7 mm, hence 0.3 mm less than previously. It seems a better fit with less pressure felt on the control wheel (see photos) In full closed position. I have reassembled everything with the old jet in the burner, and the needle just glides in and out every time the wheel is turned to the left. I just fear the old jet has a slightly larger hole than the new one, meaning it may be worn. If so I’ll get too much fuel out. But I’ll try lighting tonight.

    the other issue was the top inverted brass U mixer incandescing after 5 min of operation, which it shouldn’t I believe. So I believe my collar repair was slightly higher on one side, causing the frame to misalign with the lower top cap (the one holding the mixer tube). That might have caused the wrong stoichiometry in the mixer tube, allowing too much air through and leading to ignition inside the tube itself (hence the red glow). I will file the collar down and test the theory tonight....

    this lamp must have been my most expensive fettle to date, in terms of time, effort and money. It really has been ‘ primus madness’, but I’m truly enjoying the learning process here! 8]


    88F32E38-0619-4773-8386-918123BEC7A3.jpeg 659DB983-1589-4622-BBF7-0EC40EB0F94F.jpeg E8DC51EA-302A-43F6-868C-D0A0A784E6A3.jpeg F7C1D3F5-33DD-4506-A50A-F1A52332C9D8.jpeg D6C4E0C3-8772-4CB0-92C7-F11A98AB72B7.jpeg
     
  4. MYN

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    @Alex74
    If you look at the cross-sectional drawing of the jet again, there is an internal 4mm cylindrical guide leading to a step just before the tiny conical near the orifice.
    Your jet has a chamfered square body that's supposed to glide nicely through the 4mm cylindrical guide with its chamfered sides bearing on the cylindrical wall, while its 4 flat sides are cleared off the wall, leaving the necessary gaps as the fuel path. If the chamfered sides of the jet is unevenly worn, chances are, the needle wouldn't be centered into the orifice.
     
  5. MYN

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    ***'chamfered square could either be angled cut-offs or rounded at the four edges of the square-sided jet here.
     
  6. george

    george United States Subscriber

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    I have a 1020 1935, and there is a round piece like that on top. Under that is what looks like fiber or some kind of asbestos ring.
     
  7. Alex74

    Alex74 United Kingdom Subscriber

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    Thanks Myn,

    yes, I can see the chamfered sides on the needle. It seems to behave itself now. Nice blue flame without a mantle and then you get this with a mantle... And the new jet (so, not worn). what’s going on now? Any ideas? Please note the glowing U mixer under the hood...? Mind you, it’s going to be toasty in winter!!

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  8. Alex74

    Alex74 United Kingdom Subscriber

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    More photos with pressure up to 1.5 on the gauge and without the hood on top...

    D1C27DDB-6B19-4921-92A9-3E8A20D4A192.jpeg 7E3FE093-CE96-49B3-8AD7-AABE9F2C5FA7.jpeg
     
    Last edited by a moderator: Sep 27, 2020
  9. Tony Press

    Tony Press Australia Subscriber

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    Wo! That red glow of the j-tube does not look good. The fuel/air mix must be igniting before exiting the flame spreader (nozzle).

    Tony
     
  10. Alex74

    Alex74 United Kingdom Subscriber

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    Sorted.... I tightened the jet slightly with a spanner (it was just hand-tight before and was probably leaking extra fuel from the sides) and all seems to work well now. The lamp has been lit for over an hour with no apparent pressure loss and no more glowing parts! So silent and brighter than a Tilley. Insane.

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  11. Tony Press

    Tony Press Australia Subscriber

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    Excellent!

    Tony
     
  12. Alex74

    Alex74 United Kingdom Subscriber

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    The next one is the Veritas Superb I recently found in a junkyard. Should be fun. Watch out for a ‘Superb madness’ thread....
     
  13. MYN

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    Beautiful sight. Sometimes the old Primus can be challenging to some of us in some ways especially when not all the original parts are available when you need them. I've had my fair share with a 'hybrided' 1050 that has been converted into a kerosene-fueled lantern using parts from probably a 1080 and a 1020 or a 991. Even more so when Fogas was not within my means and I had to 'recondition' the worn jet by peening it at the orifice.
     
  14. Nils Stephenson

    Nils Stephenson Founder Member

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    Looks good Alex. :thumbup: Yes the jets on Primus lamps have to be good and tight. Once you get used to Primus lamps they seem quite simple and the result is usually very rewarding.
     
  15. Alex Smith

    Alex Smith United Kingdom Subscriber

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    Nice work Alex, great to see all is good.
     
  16. Alex74

    Alex74 United Kingdom Subscriber

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    Thanks again guys for all your help and support. It’s almost like having a bunch of like minded friends on ‘demand’ with CPL! I wish there was a similar forum for other interests of mine.
     
  17. Alex74

    Alex74 United Kingdom Subscriber

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    One month on and she still goes like a rocket. Lights up from the torch like a breeze, dead silent and bright. Nice lamp.
    4AA64374-34FB-49D0-A6F5-98D7EEBE7258.jpeg
     
  18. AussiePete

    AussiePete Australia Subscriber

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    She’s going well and I love the “Broadside” shot ......... :lol:
    Cheers
    Pete
    @Alex74
     

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