A year ago I picked up an ebay purchase, a rough Optimus 111, from a local seller who asked whether I'd be interested in this "Er, yes" I said, "How much?" "£15 too much?" says he. "No" says I, handing over the cash and leaving quickly (in case he changed his mind) eagerly clutching my purchases. The tank and burner assemblies are each held onto the vitreous enamelled steel frame by two of these round-headed brass set screws Here I'm comparing the right-hand tank and burner with the equivalent from a Radius range ... ... and with a Svea 123 to show the scale of the Cobra The operating knob. F = Fermé (closed), O = Ouvert (open) Fermé raises a pricker cleaner needle and shuts off the fuel to the jet I'm stripping a burner next to show you the innards. Each burner has a steel strut bolted to a steel lug soldered onto the tank and a heavy-duty taper union on the fuel supply pipe The control valve housing tube has flats machined on it to unscrew it from the burner and there's a conventional screwed nut arrangement to compress a carbon seal A 7 millimetre socket extracts the jet nipple The base of the burner houses the pricker rod eccentric The pricker rod has a squared-off end and not the taper often seen in such things as Coleman and Petromax generators. I think it's machined that way to act more effectively as a shut-off valve. Surprisingly, as I'll show when I fire up one of the burners, there's a subtle degree of control of the flame size possible even so TO BE CONTINUED John
Ok, concluding part. Here I've set a Cobra burner alongside - left to right - the largest silent burner I have (new old stock for a Primus No.10 stove), the regulating burner from the Radius, a silent burner from a Parasene and the little No.4 sized silent burner from my Svea 130. This group's a Cobra burner, the Primus No.10 and the Radius Neither Cobra burner had inner or outer caps and though a regular inner cap from a Primus or Optimus No.5 stove will fit, the outer cap is a loose fit and doesn't register in the depression in the burner pan, so I'm not sure exactly what pattern of caps the stove had as original equipment I've compared a Cobra non-return valve, top, with one from a Primus. Though the distance across flats is the same, the usual Primus extraction tool won't fit and I had to use one with a full width slot Ok, lighting a burner, burning paraffin. That 'pedestal' beneath the burner is an outer cap and BernieDawg's inner cap from my No.4 burner to raise the Cobra's burner to the right postion for firing. Priming was difficult. With no priming cup beneath the burners I first tried burning meths in the burner pan surrounding the caps. It didn't get the burner hot enough and I had to resort to a pre-heat from a propane torch. I reckon that when the burners and tanks are installed in the frame, it's possible to set a small tray with primer fluid in beneath each burner base. I'll probably try that some time Though you'll agree the regulator arrangement is crude compared to an Optimus 111's, say, the degree of regulation possible with this burner was staggering. Really low flame levels were possible without any indication of underburn kicking in and at the other end of the scale the caps I'd installed were overpowered by the burner John
Hi nice stove and your posts are really fantastic, brillent photos and descriptions. Just wondering what you say causes the flame to start off blue then turn yellow as its turned up? i have a burner doing that and i thought it may have been a worn jet.
Hi Cazna. Thanks for your kind words. The burner flaring like that? In the case of this stove, both burners behaved the same and the jets aren't worn, I'd judge by peering at them against the light. I think it's because the inner and outer caps aren't the orginals. Don't know what pattern they should be, but something capable of handling the power of the burner jet better than those from a Primus No.5. Likely yours could use a new jet, though silent burners can be tricky so-and-so's and I've got them to work heaps better by polishing the insides of caps and removing burrs from the cap holes on occasion. Other times, I'll swop caps around stoves and find some work better on some than others, for no apparent reason. John
Evening, Presscall, John, I can add very little to what Shagratork has said, "Stunning", indeed!! Your stuff is first rate, always, and I dearly love taking it all in!! Great photos, great information, great effort on your part, my Friend!! Brilliant! Huzzah!! Take care, and God Bless! Every Good Wish, Doc
thanks for the great pic's! where was that made? really nice, i love it. and thanks for the silent burner tips also, will definitely try them out.
Thank you very much for the post. The pictures are stunning and it's nice of you to take the time to share this wonderful piece of stove history. I really appreciate the effort and the obvious love you put into keepin' 'em runnin.' Great stove you've got there though you're probably going to hell for stealing it from the previous owner!
Hi John. Masterly post on a beautiful Range. I think this burner is perhaps overwhelming your No.5 cap at full throttle and fuel-rich mixture causes the red/yellow to creep into the flame pattern. I like you photo of different Silent burners. I did a few comparative measurements some time ago: https://classiccampstoves.com/posts/52575 Is it possible for you to estimest the size of the caps which would be an ideal fit on these burners? Thanks for posting. Best Regards, Kerophile.
Yes, George. I've measured the diameter of the burner inset, shown in the next photo as 42 millimetres. Incidentally, I've been experimenting more with 3-D photos, fabricating a tripod mount for the two Pentax compact cameras and tinkering with the image from each camera (LEFT and RIGHT) in photo software, so here's a stereo pair - click on the image and it should enlarge to the optimum size for viewing in 3-D I next measured the height of the burner 'tube' ... Here was the reading on the vernier (another stereo pair) John
Hi John, Both stereo pairs work well for me. You are obviously doing something right! Have a look at this old post and see which, if any, caps are nearest to your requirement: https://classiccampstoves.com/posts/52575 Good Luck, Best Regards, Kerophile.
Er, not quite true. Confession time. When I bought the stove it was a long time in store before I got around to digging it out for a fettle. I remembered that one burner had an inner cap when I brought it home but it had got lost in 'shed clutter' when I got around to looking at the stove. Effectively then, "... Neither Cobra burner had inner or outer caps" [BUT THAT'S BECAUSE I'D MISLAID THE ONE REMAINING INNER CAP] Well I've found it again!!! Here it is on the burner, wrong way up ... See why that wouldn't work? With an outer (top) cap on there'd be no way for the paraffin vapour to reach those outlet holes. ... and the right way up So, what to do about an outer (top) cap? One from an Optimus 5J, made by CCS's Henrik (Chickenthief), is too small a diameter A primer cup from an Optimus 111 is a (precarious) fit though With that central hole in the cup stopped up with a set screw, here's the burner on simmer ... ... and at full power Just a second inner cap and two outer caps to go ... John
Since my original post, I see that iani has uploaded this copy of a Cobra catalogue in the Stove Reference Library Cobra catalogue Sure enough, my stove's listed, and even the enamel colour scheme is named ('mauve' I guess). Great to see the burner and caps on the spares page. The image will come in handy to fabricate copies. Ditto the pot rests - well, I'll have a go! I'd wondered about the absence of spirit cups on the paraffin burners, but see that pre-heating was done with a horseshoe-shaped lighting torch dipped in spirits, like a Tilley lamp. The lighting torch is actually more like the sort used for Tito Landi lamps (also French) than the Tilley. John
Good one, I will remember the horseshoe-Shaped lighting torch dipped in spirit 1040. Too funny. Lololo
Hi, @JP2 , Is THIS the "Cobra" burner that you are seeking? If so, then please disregard all the information I posted in your thread about Marine Stoves. The burner I mentioned is also called a "Cobra" burner, but has no relationship to the burner that John has shared here. If this IS the one you want, it may be a very long time before you find one, as I think they are on the super rare side. At least to me, as I'd never seen one before @presscall posted this one. Now, I'm confused as to what you are actually looking to acquire in your Marine stove post. Take care, and God Bless! Doc
No Doc, I was doing my homework to know more about Cobra burner and then I have discovered Cobra stove. Another interesting presentation from John.
@JP2 , Ah, now I understand! Thought I'd slipped up someplace. Lots of interesting information here at CCS, and @presscall is responsible for quite a bit of it!! He's a real gem here at Classic Camp Stoves! Have a good night, and God Bless! Doc
