Hi gents, a short while ago I found an Optimus 300 for sale, complete but rather dirty (I think there is some nickel plating under the layer of dust and oxidation ). As the asking price was very reasonable I could not resist .After checking for leaks and replacing all rubber parts it was time to test the lantern. Yellow flames all over the place! I tried a few tricks like replacing the original jet with a Butterfly and a Petromax jet (both 350CP), double priming, as a last resort I even used a (campinggaz) torch to pre-heat, and even left it in situ for a while after lighting. There is no carbon deposit in the vap tube, and the air tube in the top is also free. The gap between tube & jet is correct. With or without mantle I get long yellow flames at the burner. The only thing I can think of is the jet is enlarged, and the 350CP ones are to big for this lantern. What do you think? Are 300CP jets still to be found? Any help much appreciated! Best regards, Wim
There should be no significant difference between 300 and 350cp jets. Not enough to give huge yellow flames anyway. Are the jets seating properly on the top of the vapouriser? Maybe there is some damage letting extra fuel through even though the jet is good.
Hi Nils, I've also checked this, pressurised the fount and looked for leaks at the jet and vapouriser. All is fine. Also, when turning the cleaning needle down, there is a fine stream of paraffin, going straight up. The search goes on! Best regards, Wim
Another possibility is that the narrow section of the vapouriser between the two entry points of the preston ring is worn. This could allow unvapourised kerosene to pass directly to the jet instead of via the ring.
Hi Nils, you might well be correct something is wrong there, as some brazing has been done on the upper part where the ring meets the vapourizer. In fact, my main fear is, I need a new upper part of the vap. I have a spare Butterfly one, but it is slightly shorter (about 5mm), same as the P'max vap I measured. Do you think it is possible to find an original Optimus replacement? So far I had no luck with Optimus lanterns, the first 300 I bought had a very dirty globe which turned out to be some "clear" plastic tube but it masked the fact someone hacksawed the vapouriser, and the top parts were also missing (empty hood, my guess is, someone wanted to electrocute the lantern ). But the fount is OK . Anyway, thanks for your help! Best regards, Wim
You could get it to a machine shop, they may be able to braze a bushing in place and re bore it for a reasonable price
Hi all, Thanks to Bo (Optipri) I now have a new Optimus generator (for a very reasonable price!), but we have a new problem! The new generator is about 11mm shorter than the old one! The old one is approx. 13,7cm long, the new one 12,6cm. Yet the new one is clearly marked "OPTIMUS" so original factory stuff. Does anyone know if there were different sizes in generators? The old one is clearly cobbled with, but the pricker rod looks original to the longer generator. Anyone any idea what's gone wrong? Maybe fitting a pricker rod that goes with the new generator would solve the problem, but then maybe the nipple would sit to low in the 'carburetor' (its position looks OK with the old generator). Just to prevent any confusion, this is a two-part generator, and the lantern is late 1930's (no pre-heat torch, fibre knob to control pricker). Thanks in advance for your thoughts on this! Best regards, Wim
Hi I have a few remarks on Optimus 300 I recently bought an old Optimus 300 at a market, it was/is a wreck, but with a new jet and needle, it runs fine. BUT only for a while, in 5-10 minuttes the light slowly gets weaker, the mantle gets brown/black and flames appears round the mantle. The distance between the jet and the mixintube is 14 mm. While running, I then remowed the hood, wearing a welders glove, and suddenly the light got a little brighter. I then gently blew som air into the hole where the jet sprays fuel up into the mixintube and the light was suddenly bright and perfect and the mantle was clean and white within a few seconds. I did NOT use a compressor, I just blew air gently with my mouth The lamp then ran perfectly again and I refitted the hood and everything was perfect, UNTIL 5-10 mittues later and it started all over again, the light got waeker, the mantle got black and flames appeared. I think this lamp behaves very strange and I can only think of some kind of air-mix problem, but I may be wrong Regards Niels Chr.
Hello Niels, that is a common problem with some Optimus lanterns, does your lantern make a strange noise when it starts to dim? It may be a problem with the air flow and it could also be that the lantern is overheating. However, it could also be that the lantern is not staying hot enough. What size of mantle are you using on it? Jeff.
Hello Jeff I have not registrated any strange sounds when it runs. I use 350 CP jet and needle, and 300-400 CP Veritas mantle. Now you mention temeratur,I can se the logic in the way it behaves, it is preheated by alcohol/spirit and by doing so, hot enogh, but if the mantle can´t hold the temperatur alone, it drops and the lamp will not burn properly Have I got it right Would a smaler mantle do it. Niels Chr.
Hello Niels, I would fit a 300cp jet and pricker and that may cure the problem. If the lantern is not running hot enough, then I would use a bulbous mantle and tie it so that it forms close to the vertical part of the vapouriser. If the lantern is overheating then I would fit a smaller mantle and tie it so that it forms in the centre of the ring part of the vapouriser. It's a matter of trial and error, Jeff.
Many years ago I came to the conclusion that Optimus lanterns turn mantles black because they are Optimus lanterns. With the exception of models 930 I have had the same trouble with all the big Optimus lanterns. I suspect the modern fuel available does not burn as hot and the reduced temp hardly vaporises the fuel. The solution may be therefore to add maybe 10% to 15% gasoline to the fuel or possibly use mantles that are closer to the generator tube and apply more heat. ::Neil::
I've even managed to get a 930 to burn black. It burned well the first time I lit it and I made the mistake of mentioning that here. Obviously the little ******d detected that and quickly developed black mantle disease the next time I lit it Now, both lightings were inside my house, even in the same room and the mantle hadn't changed. The only thing that did was the fuel, although I didn't record where either tankful came from and it's concievable they were from the same batch in the same jerry-can. So who knows... Now increasing the volatility of the kerosene may well help but why should I bother faffing about mixing fuels when I can get dependable light from any Bialaddin, Vapalux or Tilley (even X246Bs) in my collection...
I have a another experience with the 930 of which I have a few. All of them works fine now, 2 of them didnt for a start. I mounted a 250 cp jet and needle and a 350 mantle and that did it. I use normal kerrosene, Niels Chr. knows what type, and they just burn till empty with no problems (np David) at all. I recognize Neils problems with Optimus's but then I changed fuel from Zibro to Karmin-X and the problems stopped here also. Again Niels Chr. is familiar with that experience. Christer Carlsson is supposed to be working even developing fuel for our lamps and since he is from Schweden he might know the fuels im talking about and he surely know the 930. I bet one was hanging over his cradle. The 930 is a very nice stabil lamp that gets hot as hell (I think) and I wouldnt dare to make the fuel more explosive than it allready is with gasoline or similar. The whole tank of the 930 heats normally up so your inner securitybell rings - but they seem to work fine that way and I have never heard of accidents here or there because of the heat. Just read Podlys experiences with the 930. Claus C
Nah! I had real lamps hanging there. Primus is the way to go. Especially the two-ties or atleast the uncomplicated ones with a straight vapouriser (e.g. the 1020-family). I have many Optimus too, of course, and they work fair enough. Not worse than any other of the PX-type, and definately better than the Tilleys which I find a bit picky to get going. I guess the lamps works best in the country they were made.
No hope for me then, think I'll start collecting Lempereur & Bernard wick lamps then as no pressure lamps were ever made in my country Best regards, Wim
Hi, I too picked up an old Optimus 300CP from a market, and it also suffers from Black Mantle Disease. I've had some interesting evenings trying different jets and mantles, and had some success with a large mantle for a Petromax and having the valve turned a quarter open sort of worked, although obviously very dim. But reading here, I tried running it with the dome off, and it worked beautifully, so my solution has been to unscrew the dome from the burner, start it with out the top on, once its running quickly put the top on. So quite why that works I've no idea - maybe with the top properly fitted there's a little less airflow than with it just sat on top. Maybe the distance between the jet and the J tube changes - after all its not really locked into place. Or perhaps it just needs that little extra air to get going and then its happy. It does burn with a yellow glow, although there's no corona, so all the gas is being burnt but I guess its running at a lower temperature than my Petromax that shines white. (As an aside, the Optimus cost me 15 quid and I spent another 40 quid in packets of mantles and washer sets and so forth, and when I realized that actually a brand new lantern is only a 100 quid I ordered the Petromax. So, something worth bearing in mind the next time you seen an old Tilley sitting forlornly in a box at a boot sale :-) )
I have put the Optimus on the waiting list at the mo. The cheapo Indian P'max copy also behaved in a similar way. Basically, I did the same trick with the hood of/on and then decided (it is an el cheapo after all ) to cut away some material from the hood next to where the vap. gap is. This makes it easier for the 'carb' to breath and all problems were solved! Not a good trick with any valuable lantern though....... Best regards, Wim
I cured our 930 350cp by using a 250cp jet & needle, re-gapping the J tube, replacing the ceramic nozzle & using a coleman mantle. The 300cp has a 200 cp jet & needle, new ceramic nozzle and remains obstinate. I feel that the issue is the J tube is not easily re-gapped and the air gap is not sufficient (maybe a 150 cp jet & needle would be a better idea?). I am going to experiment a little before breaking it down for spares... (Although I do love the little 930, the tank is badly creased and dented so I won't feel that bad about scrapping it!)
I reckon most of the Optimus problems are because of a choked Preston loop. We know 930 lamps generally are good and they don't have provision to change the air gap. I hear of people making sure everything else is cleaned out and they still don't run right. I therefore assume that having to change the jet to a smaller one suggests there is a generator problem and since you can't see inside the loop I wonder if that is where the problems lie. ::Neil::
Preston loop has been cleaned with wire & carb cleaner. I'm going to have another go at it though & see if it meets with any success! Some caustic soda beckons...
I am starting to suspect that this problem could be caused by the fit between the cleaning rod and the narrow section of the vapouriser between the preston loop ends. If this is too worn (or too big from the factory) then there will be excess liquid kerosene getting past.
Noiw there's a thought. The quantity should not matter but too big a gap there will mean little or no fuel passing through the loop so the resultant gas will be too cool perhaps? Might be an idea to swap round a few rods to see if there are any changes to the burn. ::Neil::
I too have an Optumus 300 and it works reasonably with a Colman mantel, all be it not as bright as other brands of lantin. I have never had the black mantle disease or other problems with it. I think it is about a 1945 one as it has a soldered brass plark on the font with somebody's enitials and the 1945 date on it. The chrome is very ordinary. I choose to use other lamps in preference because it is not as bright. Reading the comments on the lamp is very interesting, hope you all get a sesolve on your problems. Cheers Rob
Until the cleaning needle broke my 930 always ran perfectly, but I did notice the mantle can go black if the pressure drops... I've no idea why this should be but it is definitely the case on mine.
