These 7-pint capacity stoves equipped with burner No.4142 are rare enough to justify this listing for reference purposes and they enable me to offer some interesting insights into Primus's largest silent burner equipped 'household' paraffin stove. AR date stamp, 1952, and tank engraving. The silent burner line-up. The Liberty burner from India, far right, is an oddball outsize dwarfing even the 4142 alongside it. In THIS POST I had something of a job on my hands getting one of those Liberty giants not to underburn. The burner in the middle there is another Liberty branded product, pretty much of the same size as the Primus 4142. Left of that is a Primus 4140 (from a Primus No.10 stove) and far left is the common Primus 4138 (equips a Primus No.5). The better quality of the Primus 4142 compared to both Liberty burners is most apparent viewed from the underside. The jet in the 4142 has a 0.5mm orifice (or 0.49mm as @shagratork determined from a source once) and it's smaller externally than the jet equipped with hexagonal flats in a No.4140. Missing its inner and outer caps (part nos. 4681 and 4208 respectively) I adapted a spare inner cap - part no. 4678 - from a 4140 burner and the outer cap (part no. 4206) from the latter fit straight on. Though having the same capacity of 7-pints, the Primus No.3 has a beefier roarer burner supplied by a larger bore riser tube (No.3 on right). Burner (part no. 4131) from the No.3 stove in the middle, burner from the No.8 on the left and the large Liberty burner which will fit the No.3 riser tube but is too large for that on the No.8. One final point. The pot rest/legs are longer on the No.3 than those on the No.8. Different part numbers as is evident from the schematic and part lists for the stoves. So, a burner test. For convenience I mounted the burner on a Primus No.5. ... which required a lot less fuel for a test firing. Simmer. Full blast. Lit up the night. John
Apologies in advance for ignorance - in the No8 diagram, part 4281... ...would that be some kind of clip on pilot light, a tube from the preheater cup to the burner to provide a flame to light the burner when turned on, after the preheat ? Has anyone/does anyone use one ? Are they available, can I fab one from some microbore copper ? Are there jets or capillary material involved ?
@shocker Correct. It is a pilot tight. Various types are available online on eBay - make sure you get the correct one for your burner. Cheers Tony
Thanks Tony, nice one mate ! Now does anyone know what they consist of and how they work so I can make one myself ?
Tried searching the bay with part #s and "pilot light/lamp/tube" and found none .What is the correct nomenclature en anglais ?
Found some and more importantly, some pics. Soooo...a folding arm type bulldog clip, cupronickel brake pipe and some wick material...mix thoroughly and cook on gas (paraffin) mark "whoooosh"
@presscall In my own notes, I certainly had the jet size written down as 0.49mm. I can't remember where I got that information from. Maybe it was from information posted by a member, or in a publication, or maybe it was from me measuring a couple of appropriate jets. However, I have changed the size of the jet in my notes since @Tony Press posted a pricker packet here. The Primus No.8 uses the 4393 nipple. So does the Primus No.2. The pricker packet states that the jet size for a No.2 is 0.40mm.
Personally I assume that the 0.40 is the wire size and not the jet size. I would think the wire should be slightly smaller than the jet's hole. If they are the same size the pricker will be difficult to use or even get stuck. Am I thinking wrong? Michael
@cmb56, @shagratork & @presscall I will measure the 0.40 pricker tonight when I get home (vernier calipers - still waiting for my micrometer); but in this post below Optimus calls the pricker for the 0.96 etc. 0.23mm (I will measure it, too). https://classiccampstoves.com/threads/optimus-pricker-for-0-23mm-jet.34951/ Cheers Tony
Regarding the jet size, when I quoted the 0.5mm that was from actual measurement. I tried a number of micro-drills of increasing diameter until one was a snug fit. I'd judge the burner and jet are little, if not unused, and the combustion is good. The yellow/orange in the flame shots is not due to unburnt fuel (no yellow in the flamelets) but to the phenomenon of that massive burner shroud glowing red and imparting colour to the flames - much as happens when a flame from a modern bottle or canister stove impinges on a pot rest, notably THIS example from Hikin Jim. The variable I've introduced is that the burner caps aren't the right ones. The inner one must be close to specification and the diameter of the outer cap must be about right (limited by the requirement not to overlap the burner skirt base slots) but maybe should be a bit taller? That said, the evidence of good combustion as it is suggests the outer cap's not too mismatched to the burner requirements. John
@shagratork, @presscall & @cmb56 I just measured the 2452 pricker with vernier calipers as 0.30 to 0.31mm. Cheers Tony
Er, no, the size of the jet is 0.5mm. It's a big burner with plenty of capacity to burn the fuel that jet injects.
@presscall I forgot that we talked about your burner. I was concentrating on Tony's pricker. Sorry for that. Michael
@Rangie Lucky for me, Alec, yes. £6.50 didn't break the bank and the seller only lived six miles away. I think I read in one of your posts you have a Primus No.6 or No.7? If so and it has the 4120 burner with the original caps could you measure them, particularly the height and diameter of the outer one? Maybe a photo or two? Cheers, John
@presscall , I have a couple of 6s, but no 7 (or an 8, dammit). One took an incredible amount of persuasion/cleaning to remove the caps from the burner, the 4208 not so bad but the 4681 was welded on with rust/rot. Both caps, however electrolysised (sp?) and polished up very well and are useable. Photos/measurements, I will remember, I will remember, I will remember...... Alec.