Here are two of my Petromax 829s. The one on the left is a modern Chinese one which worked when I got it and then never again, until today. The other is a proper German made one. For some reason the Chinese one stopped working on it's first ever run, all I could get from it was some serious black mantle disease. It worked once since then when Mr Kl80 tried one of his inner hood assemblies on it. Today I tried it again with all the original parts and just swapped the jet and cleaning needle from 500cp to a 350cp. Heypresto, it works as well as it's German cousin. Don't know why, all I know is I'm happy. A question. How important is the air gap above the jet? In the pictures, it is running with a gap less than that specified for a 250cp lamp according to the Petromax tool. I can't adjust it because the screw that holds the "J" tube is seized up and the only option will be to break the bolt and renew. Is it worth doing and will it make the lamp run noticably brighter? Here are some pictures for your approval and even a Link to a video. These are some seriously noisy lamps. Oh and the whine in the background is the washing machine on spin cycle, didn't think the camera would pick that up over the lamps.
The gap determines the air/fuel ratio, so it's fairly important to have it set properly. With it set to the gap you have it's will be running too rich and you will get things like an orange halo around the mantle, black mantles and generally poor performance. Strangely, it doesn't look too bad in the video. The bolt that secures the J-tube is a cheap part, so if you can't free it up it's probably worth breaking it just to improve the performance of the lamp.
Yes Pods, most of the noise is the lamps, sounds like staring on the Tv. It's the whine you hear that changes note in the background that is the washing machine. Thanks HD, I thought it probably would be important, but was of the "if it ain't broke don't fix it" thinking. When I tried to check the gap, I was surprised by just how small it actually was and that it worked like that knowing how finicky these lamps can be. I'll have a look through my parts and see if I've got an inner hood somewhere, I'm sure I have a scrap hipolito in the shed.
Too late to edit the post above this now, but what I meant to say was it sounds like static on the Tv. Just had another fiddle now everything has cooled down. I took the inner hood from the chinese lamp and placed it on the German lamp (with 500cp jet). With this burner I can adjust the air gap, so I adjusted it spot on and lit the lamp, no problems. Then when I tried to fit the outer hood to the lamp the light dulled and wouldn't pick up. Removed the outer hood and back to full brightness. So with the lamp running I adjusted the gap to bigger than the recommended as there was clearly not enough air for combustion. Still the light dulled when I tried to fit the outer hood. So it would appear that with this combination the outer hood restricts the air too much. Now back to the German inner hood, I looked to see how much adjustment room there is if I changed the siezed up screw, and well as the pictures below shows there is no room between the mixing chamber and the hood bracket. Picture left is chinese hood, plenty of room for adjustment, right image German hood no room for adjustment. I guess there's no point doing anything with that screw.
Putting the Chinese hood/German Petromax issue to one side for now because it muddies the water a bit. If the gap on the German Petromax hood is so narrow and there is no scope for adjustment then it sort of suggests that that J-tube was never meant for that lamp. I would consider replacing the J-tube, mixing chamber and nozzle with the ones from your Hipolito and fitting a new jet and needle and starting from scratch. I might be tempted to clean the upper vapouriser and preston loop too.
Thanks HD, these lamps with their varying air gaps are a little different to the Tilley's and vapalux lamps that I'm used to. I'll find the hipolito sometime and have a swap round of parts, see what happens. Thanks again, Matt.
Yes, the Petromax type lamps can be time consuming to fettle, but once they are, they perform really well.
After much pain with mine, I'd leave it alone if it's working. It'll probably stop working soon anyway giving you an excuse to fettle/play but whilst all is working, I'd leave it thus! These lamps are fickle beasts at the best of times
The Petromax type of lanterns can be irritating to set up, but once they are fettled properly they are excellent!
Since the J-tubes are still quite easy to get why don't you just cut off a small piece from what extends into the mixing chamber? Only take care to deburr it properly because otherwise it could disturb the gas flow.
Honestly, if it is working and giving a good flame & a bright mantle, why mess around with it? If it does burn well, it will be getting enough air for the fuel being injected into the J tube. It's one thing to use a spare top & experiment, but personally I'd leave well alone (for now). I'd also not be cutting into the original J tube unless as a last resort to try to get a non-runner working properly (and even then I'd get a spare & do surgery on that)!
The adjuster screw will free up with a heat and quench. Just get it dull red hot and dunk in cold water. One thing you might look at is the J tube where this screw grips it. They do sometimes dish in there and that can affect the gas flow. ::Neil::
