Yes, I meant to say after my black oxide bit - so more likely above the burner than below. You got it sorted, though and that's the main thing. It was early, which makes a change from my usual excuse - 'it was late'...
@Henrik The "silvery washer" is aluminium and it should have a fibre washer under it. Fibre is used there so it doesn't damage the enamel.
Henrik, I have a very similar washer under the same nut, so I bet that’s where it goes! Nils, Back to the fettling table and I just did what you have suggested. Sliding a new needle up the jet by hand, there is a ‘step’ or little obstruction in the new jet but not the old jet. I can’t quite shine a light inside them to take a closer look. I have also made a more robust ( less Heath Robinson) threaded coupler which enabled me to adjust the overall rob length to 154.7 mm, hence 0.3 mm less than previously. It seems a better fit with less pressure felt on the control wheel (see photos) In full closed position. I have reassembled everything with the old jet in the burner, and the needle just glides in and out every time the wheel is turned to the left. I just fear the old jet has a slightly larger hole than the new one, meaning it may be worn. If so I’ll get too much fuel out. But I’ll try lighting tonight. the other issue was the top inverted brass U mixer incandescing after 5 min of operation, which it shouldn’t I believe. So I believe my collar repair was slightly higher on one side, causing the frame to misalign with the lower top cap (the one holding the mixer tube). That might have caused the wrong stoichiometry in the mixer tube, allowing too much air through and leading to ignition inside the tube itself (hence the red glow). I will file the collar down and test the theory tonight.... this lamp must have been my most expensive fettle to date, in terms of time, effort and money. It really has been ‘ primus madness’, but I’m truly enjoying the learning process here!
@Alex74 If you look at the cross-sectional drawing of the jet again, there is an internal 4mm cylindrical guide leading to a step just before the tiny conical near the orifice. Your jet has a chamfered square body that's supposed to glide nicely through the 4mm cylindrical guide with its chamfered sides bearing on the cylindrical wall, while its 4 flat sides are cleared off the wall, leaving the necessary gaps as the fuel path. If the chamfered sides of the jet is unevenly worn, chances are, the needle wouldn't be centered into the orifice.
***'chamfered square could either be angled cut-offs or rounded at the four edges of the square-sided jet here.
I have a 1020 1935, and there is a round piece like that on top. Under that is what looks like fiber or some kind of asbestos ring.
Thanks Myn, yes, I can see the chamfered sides on the needle. It seems to behave itself now. Nice blue flame without a mantle and then you get this with a mantle... And the new jet (so, not worn). what’s going on now? Any ideas? Please note the glowing U mixer under the hood...? Mind you, it’s going to be toasty in winter!!
Wo! That red glow of the j-tube does not look good. The fuel/air mix must be igniting before exiting the flame spreader (nozzle). Tony
Sorted.... I tightened the jet slightly with a spanner (it was just hand-tight before and was probably leaking extra fuel from the sides) and all seems to work well now. The lamp has been lit for over an hour with no apparent pressure loss and no more glowing parts! So silent and brighter than a Tilley. Insane.
The next one is the Veritas Superb I recently found in a junkyard. Should be fun. Watch out for a ‘Superb madness’ thread....
Beautiful sight. Sometimes the old Primus can be challenging to some of us in some ways especially when not all the original parts are available when you need them. I've had my fair share with a 'hybrided' 1050 that has been converted into a kerosene-fueled lantern using parts from probably a 1080 and a 1020 or a 991. Even more so when Fogas was not within my means and I had to 'recondition' the worn jet by peening it at the orifice.
Looks good Alex. Yes the jets on Primus lamps have to be good and tight. Once you get used to Primus lamps they seem quite simple and the result is usually very rewarding.
Thanks again guys for all your help and support. It’s almost like having a bunch of like minded friends on ‘demand’ with CPL! I wish there was a similar forum for other interests of mine.
One month on and she still goes like a rocket. Lights up from the torch like a breeze, dead silent and bright. Nice lamp.
I would like to continue this thread because it handles pretty much about Primus 981 and its preheater. So I have two 981´s, both AD 1939. The first one had a very bad fuel tank but a green top as new and a preheater with the metal knob secured with a nut. Ik took that one apart hoping to find a next one having a fuel tank in reasonable shape. The second one came a few weeks ago, with a fuel tank in well used state but I could start a rebuild of a 981. I fixed the nrv, pump leather, and began cleaning the preheater, the one with the metal lever, the oldest version. Screwing the preheater in place on an 981 is a bit tricky, a complete one cannot make the whole turn, the spindle, nuts lever and nut can only be mounted with the preheater almost in place. But the result is that the preheater cannot be operated, the small nut holding the lever in place is touching the tank. I took the other preheater instead, the one with the black lever, even that one is very close, but not touching the tank. Another question is the wheel on the spindle to light the lamp and moving the cleaning needle down. The only way the wheel can be fitted is with the text Primus Sweden facing the lamp, not visible for anyone looking at the lamp. I wonder, is it meant this way, I found it impossible to mount the wheel with the text facing out. Regards, Ton.
Now I managed to get the first type of preheater, the one with the metal lever in place, and working. I must admit I used gas tape in order to make the preheater fit in place in the fuel tank some turns earlier. In that way the preheater i sticking out a little bit more, making it possible to fit the lever and nut and be able to open and close it. Another point on those lamps is finding the right adjustment in the way that the spindle shuts down the fuel flow and the cleaning needle just sticking out of the jet when turning the wheel to the right. But she, or he, is burning now, I am satisfied so far.
