I have 3 or 4 Primus 71s and a couple of Optimus 80s and I will say the thread has awakened my interest in them. Truth to tell, I've never lit any of them, and haven't looked at them for a long time; I'll search them out in my (tiny) version of the Hobbit hole.... My most-used stove over the years is a Svea 123, the most familiar of the Swedish single-burner petrol family. I have taken it on almost every backpacking trip in the last 9 years. But, of course, it is part of a Sigg set. With such a set, these are the most useful of stoves. Without one, their utility falls dramatically, because of their gravitational instability; i.e., with my dinner on one, it would be sure to tip over. The tall 71s would seem to aggravate the problem. Does anybody have much experience with these (i.e., the 71s and 80s) as a regular hiking user? I'd be interested in their experiences. While Svea 123s were long familiar here, I never saw the others until I became a "collector" here at CCS....
Don't you think that even if tapping was carried out by hand the tap would be fitted with a stop? Even something as crude as 2nuts tightened against one another at the appropriate point on the tap shaft? Filter assemblers, even the skilled ones, always needed such aids - usually devised by the production engineer. If the position moved I guess somebody changed the tooling or maybe the nuts worked loose and the 'erks' reset them by themselves?!.
Hello JonD Yes sure, the threads were not made without support. But the process is more complex as it looks like at first appearance. Remember the upper part of the tank was a flat brass sheet first. Then it was shaped to a bell-shaped thing with a depression in the middle, the spirit cup. Now the problem is, how to get enough material in there, to make the female thread with. Usually in industrial production such threads are not cut with a tap, as we do it at home, but "rolled" (?) (chip-less forming). I don't know how Primus made it, and probably they did it not always in the same way during the 40 years. Best Regards Radler
Thx again Ray, Trevor, all, At least 2 opinions are expressed re valve position. As mentioned I'll not say it's a conclusion. I don't see certainty on either side of discussion, I don't see a wrong or right and I do respect fellow stovie's various opinions shared, on-topic. I do still happen to fall-in w/Primus being consistent to exacting standards. I post to add some addl. points one being: I think, much of assembly was "piece work" needing to pass inspection. Also when/if changes were implemented it was a change to the setup for the assembly line, imo. Comments re tapered fit and the valve position the assembler found it "tight enough" would vary. Responses to that already included explaining the production/tooling setup, which makes sense. I post to add 2 points: on assembly line both male and female > the threads were new freshly cut. New brass threads will have wider range "to tighten" (more turning of the wrench between snug and too tight). New threads snug-up and seal differently / better (fettlers aligning a valve deal w/used threads, which is different than new threads). > The "hardness" of the new brass, which (softer) also allows for more adjustment / wider range. I thought hardness might be applicable here re new, unfired stoves. It is likely imo, new threads allowed assemblers to snug-it, then all examples have enough tightening range to then advance all the valves to the same alignment that the assembly line was producing at the time (w/o over tightening). fwiw I DO also think Primus, by-design, was mindful of maintenance and that owners dealing with USED worn threads could tighten it just enough, resulting in varied positions, and is fine, so long as it achieves a seal and is clear of tank lid. thx omc PS I DO appreciate efforts to keep the peace. Others have chose to ignore. I can and have ignored some jabs in the past, there are instances where that is easier said than done. IE when you're the one getting falsely negatively hit. Part of this: if myself and others can in future resist posting solely to pile-on a criticism of others... I think would be a good step. Peace, yes.
Hello all I am Allan from Denmark, and a very new member here. Since my days of being a boy scout I have had much use of a Primus 71...stamped AS in the bottom. Is it possible to date it ?
Thank you so much, Ray123. My 71 have been a very reliable companion always, when hitch hiking and camping all over Europe. This little fellow always draws attention when firing up at a camping place, among all the gas burners :O)
@Alsendk It looks like you are asking about the soldered pin/wire on the tank. It is an older version of the over-pressure valve. There is a good description of how it works elsewhere on this site. Note that the gas cap lacks a safety release valve as in seen on later models of this stove and several other. As I understand it, the wire is attached to the bottom of the tank and protrudes through the top where it is sealed with a little solder. If heat and pressure get to be too high, the solder seal fails and/or the wire is pulled free of the seal and vapor is released before the brass tank fails. I've yet to hear of someone putting it to a test.
Thanks, Itchy. it makes sense...primitive, but it might work. And I wouldn`t want to be near it if it should ever explode
Interesting. I have read the very long thread about where the valve is placed, compared to the filler cap. And I see it placed in a lot of different positions. But when placed in the tin can, both the valve feeding pin, and the filling cap are strategically placed in a position, so I am able - both to refill the kettle, and close the tin box, due to the feeding pin being placed to the side, which makes it possible to close the tin box door. This means that it is not being necessary to take out the stove for refilling. Very practical ... but this is far from being the rule I see. Sorry for the words used for describing technical terms. It might be confusing to read. English isn't my native speaking language.
Interesting this thread, I have only one 71. I got it about a year ago from a deceased estate where the son was selling everything. He knew nothing about the stove. I have only replaced the washer in the fuel lid and lubercated nipped up the spindle. I cannot find any serial number or date stamp on it. I assume it had not been fettled before but don’t really know. I left the wick alone . It works great. I can not date it with no numbers to go on. I may have missed something in the previous posts but don’t know. Someone may chime in as to the date from the things on it. It has Bacho only on the lid. Made in Sweden on the tank. The spindle is located opposite the filler plug. Cheers Rob
Hi @Robert Bruce . You should have looked through the Pr.71 stoves and cases in the Reference Gallery for a similar stove. I reckon your nice Pr.71 was likely manufactured between 1955 and the early 1960s The decal on the front of your tin says “AB BAHCO STOCKHOLM SWEDEN. B.A.Hjorth & Co changed their name to the initials BAHCO in 1955 & this was reflected on the famous logo. In 1962 Optimus acquired the Primus brand and after a transition phase, where existing stocks of stoves and parts were used up, re-branded their Optimus No.80 as a Primus 71. You say there is no date code or marking on the stove. It is worth having a look on the front edge of the lid, as these later Bahco marked Pr.71 outfits sometimes had a date coding on the case. Trust this helps. Best Regards, Kerophile.
Kerophile, thanks for the information, also I have looked on the case to for a date or code and nothing. I have found similar stoves in the reference gallery but none with no dates the same. Maby I have missed something ? Just curious as to a date as it should be easy for Primus, it shouldent be like other makes that don’t have serial or date codes on them. So between 1955 and 1960 is ok to me and seems ok. Strange that Primus put codes or dates on all others but not this one. Possibly it got overlooked, and as I don’t know much about the 71 in general this was this par for the course.? Cheers Rob
Hi Rob, there are other Pr.71 stoves in the reference gallery, with no date codes so yours is not that unusual. https://classiccampstoves.com/threads/1955-primus-71l-last-of-the-hjorth.22036/ https://classiccampstoves.com/threads/1933-37-primus-71-no-date-stamp.34923/ https://classiccampstoves.com/threads/primus-no-71-1937-directions-for-use.32627/#post-333110 https://classiccampstoves.com/threads/1962-primus-71.31406/#post-319068 And there are more! If you look at this Primus dating table and text: https://classiccampstoves.com/threads/primus-dating-chart-1911-1964.11464/ “Primus Dating Chart - From 1911 Primus paraffin stoves are stamped with a letter code. This is found under the tank. The codes Q & AQ are not used. From 1955 a six digit number was used, the last two digits corresponding to the year. This stamp is often found on the leg or burner riser tube depending on model. The code was also used on the petrol model No:71 but not from the first years of production. With regard to the later 6 digit date code it would appear that post-1964 the code may have been continued but stamped on the cardboard box rather than the stove.” So, your stove dates from 1955 -Early 1960s, and you would be looking for six digit number, with the last two digits giving the year of production. This number was sometimes impressed on the case of the No.71 stove, usually the lid, or even on the cardboard box the stove was shipped in. Here is a link to a 1960 Primus No.71 with the date code marked on the inside of the case lid: https://classiccampstoves.com/threads/dating-primus-71.30352/#post-308317 Here is another Primus No.71 this time from 1958,and the date code is on the outside of the lid of the case: https://classiccampstoves.com/threads/1958-primus-no-71l.13262/ If dates were stamped or marked on the case of Primus 71 stoves it is quite possible that subsequent corrosion and heat damage may have damaged or obliterated the markings. Best Regards, Kerophile.
Ken, How do you get the spindle to line up. I ask this because I , with age find that I can't always line up even if I mark the spot. do you use some type of vice or all by hand. my hand strength is not like it was in my early years. Let me know if you are all by hand or use some type of vice. I know that some people have made special Grips or Jigs for their Vice's just to hold a 123 or 71. Anyone who has a good idea ...I could use help with this Thanks ECHO1
Thanks to all who contributed. Robert Bruce, An exact match to yours, another undated complete unfired P71 recently sold on ebay. I was in contact w/seller, his also with no date markings on stove or tin. The OP is re vaporizer position and this too is rare with your example having the valve position opposite the filler cap. It is an example I've now seen several of over many years. SO your "I assume it had not been fettled before..." rings true for me. and me: ""> Then late 54 thru 56 P71 was again a consistent product imo. > After that, maybe late 56?, but c1957/58 for sure it gets a lil goofy again. c57/58 is when there are "some" undated P71s and that change was not straight forward either. I've seen an undated 58 and a dated AX '58. I've not seen a date stamped AW 1957 reg sz. P71. Has anyone else? "" CCS source thx omc view count 4300
Thanks to all have contributed, yes I indeed have missed details in the reference gallery, oh well it’s a age thing but now see. Cheers Rob
@ECHO1 I line the spindle up by: 1. Marking the position before dismantling; 2. Counting the rotations while dismantling; 3. Replacing the burner first by easy hand tightening; then, 4. Finishing tightening with a correct fitting, good quality spanner. Cheers Tony
