Silent burner questions

Discussion in 'Stove Forum' started by Jim Lukowski, Jul 29, 2018.

  1. Jim Lukowski

    Jim Lukowski United States Subscriber

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    I'm working on a buddy's Primus 54 with silent burner and have some questions. I don't know the history of this stove but it's obvious that the inner cap is not original, and also obvious to me that it's the issue with this stove.

    Inner caps.jpg

    As you can see in the above pic, the cap on the left which came with the stove isn't concave like the one from my Primus 54. Not only that, but the center hole isn't a large enough diameter to go over the burner riser tube (whatever that's properly called).

    Here's a pic of it burning with the inner cap on the left, and then a proper inner cap on the right.

    Burning poorly.jpg Burning well.jpg

    My questions:

    1) Is there a proper name for that inner cap?
    2) Does anyone sell it separate from the outer cap? I couldn't find one at The Fettle Box, but maybe that part has a specific name.
    3) Do you think that if the inner cap hole hole were widened so it would fit over the tube, that would resolve the issue?
    4) If yes to 3), would the top of the inner cap need to be concave also?

    Speculation is fine. :)

    Thanks,
    -Jim
     
  2. dspearsy2k

    dspearsy2k United States Subscriber

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    To answer the questions. 1.) no or mis-manufactured, it's missed a step in manufacture. 2.) not normally,
    They are normally sold paired with an outer cap. and it does not have a specific name. 3.) Yes, if
    there is enough space for gas flow between inner and outer caps. 4.) no, The shape is made by a sizing
    punch in manufacturing. (the missed step in the manufacture of your inner cap). As an note, there is a different inner cap with holes in the top. they perform no function unless paired with a burner with holes in the mixing tube. (The riser goes between the fount and the burner). The paired holes help extinguish under-burn.
     
  3. Ray123

    Ray123 Subscriber

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    To answer question 2, I've never seen burner caps sold in a paired set. I've always bought them separately. Basecamp and Julian on eBay will have them. Fettlebox may be out but I've bought both inner and outer caps from Ross. Send an email to inquire.
    If you can open up the one you've pictured with a file I'm sure it'll work fine.
     
  4. snwcmpr

    snwcmpr SotM Winner Subscriber

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    Left one looks taller. Is it?
     
  5. Jim Lukowski

    Jim Lukowski United States Subscriber

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    It appears that the one on the left is at least 1/8" taller. I found out my buddy has other stoves/parts, so this is no longer critical. However, since this inner cap isn't usable as is, I was thinking I would try to mod this using a couple of sockets. A larger one below to hold this inner cap, and hammer down the center area with a smaller one to make it a bit concave. After that, I can try to ream it out a little more.
     
  6. snwcmpr

    snwcmpr SotM Winner Subscriber

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    I would make sure this inner cap does not fit one of his other stoves before modifying it. Maybe it got mixed up at some time.
    I also try to get/buy/find/steal an original part before I make a part. But, that is me.
     
  7. Jim Lukowski

    Jim Lukowski United States Subscriber

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    Thank you snwcmpr! That's something I had not even thought of.

    Edit: He's searching for a correct one now.
     
    Last edited: Jul 30, 2018
  8. aomb30

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    The non-fitting cap might be from something like a Seaward Princess alcohol boat stove. They have that profile and are a bit small for the tubes on Primus stoves.
     
  9. shagratork

    shagratork United Kingdom Moderator, R.I.P. Subscriber

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  10. Jim Lukowski

    Jim Lukowski United States Subscriber

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    @aomb30, thanks for bringing that up. It turns out he does have an alcohol stove, but doesn't think it's missing anything. I've asked him to double check.

    Trevor, thanks for the link. I could have sworn I looked at Juliands, but didn't see the cap. At this point, I'm waiting to see if my buddy already has the right inner cap.