I have just obtained a Optimus 350/350CP lamp that was boxed with all its original spare parts tool and instructions, I think it is of recent manufacture 1970's ? and has had little use. I have tried to get it going a few times but it pulses badly (you can hear it and see it) I tried increasing the number of pumps from 30 to 60 and this improves things. It will run for about 30min then the mantle starts getting black and turns to an orange flame rotating the tip cleaner does not help. I have cleaned the tank with vinegar, as it had a black varnish like deposit all over the internal surfaces, cleaned and checked all parts. I am not sure what to do next any suggestions? The only other question is where can I get a new seals for this lamp as the ones on there are not brilliant and I suspect this may be a cause of my problem. I have tried all the normal suppliers but cant find seals for this lamp. Peter.
Any chance of a picture? That will help in placing it in the timeline. The 350 was produced from 1957 to the 1970s. Has it lost pressure when it starts to burn badly? The only seal that might need replacing is the filler cap washer. Ross has quite a selection listed in the trading post and if it's not there I'm sure he can make one. Otherwise just check that everything is tight. Mostly to admin: If we could see the member's location it would help to advise where to get parts etc.
Nils There appears to be a fair degree of pressure still in the tank when the problem occurs, but how much I don't know. I think I need to replace all the seals to eliminate air loss as a possible cause Is there any particular part of the lamp you would like me to show in the photo for dating. For info I am in the south east of England. Peter.
A good picture of the whole lantern would be good, but it's the control wheel and the label on the collar that are the main indictors. As far as seals go, the 350 only has three. The filler cap washer, a lead washer under the vaporiser and the seal in the pump non return valve. It's easy enough to check for any leaks. Just remove the top and glass cage so you're left with the tank with the vaporiser attached. Pump up the tank with no fuel in it, remove the pump then put it in a bucket of water. Any leaks will be obvious.
Nils I had problems uploading picutres of good quality so have attached photobucket links, I hope this works OK. Peter.
Looks like it is one of the last made. Probably from the 70s. Very nice condition. Uploading pictures can be a bit tricky the first time, but once you work it out, it's easy. The mantle looks a bit small. What type are you using? I can see a bit of soot around the lighting hole so I assume you light it with matches. I have found that the sulphur gases and whatever else there are in matches can attack the brass and over time cause corrosion. I always use a lighter (one of those long necked type for lighting candles) as the burning gas doesn't have these corrosive products.
Black mantles are a problem with a lot of Optimus stuff. I have had some trouble with several of mine like that. Might be worth checking the air gap. Not sure what it should be for an Optimus 350 but I guess it will be the same as a Petromax so 13mm from top of gas jet to start of venturi tube will be about right. It may also help to clean off the top of the jet. Sounds daft but i fthe jet hole gets out of shape then the gas stream is not even and that can affect the burn quality. Trick is to gently lap it down on an oild stone until it is clean. No more because there is not much metal there but some times doing this can make a big difference in the burn. Bring it to Newark and I am sure there will be plenty of guys there who can make it right. ::Neil::
Nils I thought this lamp was a recent one but thanks for the confirmation. The mantles are the original Optimus No4 supplied with the lamp. I do have Coleman #99 and some older silk versions (I don't know what the difference is) would these be better?. I think the stains round the lighting hole are from the spill I use for lighting as I don't normally use matches. Neil I did try and adjust the air gap and it did make a difference. I am also rebuilding a Petromax lamp and found that they recommend a specific gap height, so as you suggest, I will adjust it to the same setting. I will try and lap the jet face one night this week and then bring the lamp it to Newark and look for advice. Its a nice looking lamp and I don't want to give up on it like my Veritas Superb which has similar problems. Peter
Optimus No.4 mantles are for 250cp. For 350cp, the original Optimus mantle is No. 4a. Any 350cp round shaped mantle will work fine. As long as there are no leaks and the air gap is right (13mm is correct), there isn't much else to do. Lapping the top of the jet is a good idea, but it needs to be a very fine stone.
Nils I checked the mantle packets and they are No4 250CP, odd as they appear to be original ones supplied with the lamp. What difference will this make, would it just be a lower light output? Do you know what the physical difference is between a 250 and say a 500CP mantle. Peter.
Basically, the light output is proportional to the surface area of the mantle. To fill the volume of the mantle requires a burner of the correct size, or you could say that a burner of a specific size requires a mantle with the correct volume to give the optimal light output. If the mantle is too big, then it will not be 'filled' fully and the light output will be low. If the mantle is too small, then the flame will burn outside the mantle, also giving poor performance. In your case with the mantle being too small, it could burn correctly by having a lower pressure but this introduces another problem (which sounds like what you experience). With a small mantle and low pressure it is likely that there is not enough heat transferred to the vaporiser which will end with liquid fuel coming out the jet giving large orange sooty flames.
If you will be stripping it down to clean, check the vaporizer tube as it may be gunked up. I just finished a hybrid lantern and I heat and quenched the vaporizer. To my surprise a lot of black pieces of gunk came out. When I fired up the lantern it ran very well. Hybrind because the tank is coleman while the rest is a 182 petromax. Ron
It is always a surpise just how much crap you can remove from a generator like that. However a note of caution. Those Preston Ring generators are silver soldered or brazed together and if you get the top part too hot where the ring is welded on you can melt the seal. So dull red hot only up there. ::Neil::
Yup, am aware so I really do not heat it to a point and only use propane to heat it up to a point that the silbrazed joints are not affected. Ron
