ARMY #7 BURNER HEIGHT/PHOTO QUESTION

I'm sure we all know these 3 stoves--i bought the case for the Army #7 from
ebay and following the directions on this this site swaped tanks and burners to
come up with a stove that would fit into the case--
the 71 burner is flush with the top of the case--the 80 comes up the pot holder
about half way and the same with the Army #7---
have i got it right????

 

Hi Dave, they all work, but the real thing is

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I've set that up now, but really can't see a difference to be honest mate

 

Rik, it seems to me that yours is about right, you do need a sufficient gap between burner top and cooking pot. I ended up with a 71 tank and a 123r top end, & it looks the same as yours for height.

 

Hi Jules

This is the pucker kit, an 80 stove base with a 123 burner head





It burns like a good un 8)

 

Hi

Unless I am completely misunderstanding the instructions in the case the correct stove seems to have been a military version of the later 80 stoves. It makes no mention of separate prickers so the correct stove is an 80 tank with a Svea 123R burner on it.

Please let me know if anyone has any positive information that contradicts this.

80s and 71s will work in the case but do not fit the instructions in the cover

Regards Bryan

 

Nice pics Rik. Bryan, I've just had a look at mine, definitely has to be a 123R burner, on the label- cleaning instruction 2 confirms this, as does a look on the search facility.
So now I need a 80 tank, getting expensive is this stove.

 

Hi Jules

I am in exactly the same position. I need a late 80 tank with the sticker. I bought several tins. When I bought them there had often been both 80s and 123Rs up for sale. After buying the ins I have managed to get one 123R but no 80s. I do have one correct combination made up but would like to complete some of the other outfits.

You can resell the 123R tank with the 80 burner to help recoup the expense. I prefer the non internal pricker burner in any case.

Regards Bryan

 

Good Morning, Bryan, and All,

Interesting thread!

I may be showing my ignorance here (yet again!), but aren't the threaded portions of both burners a different size? I just took cursory measurements across the threads of a 71 and a 123R burner, and the 71 measures 9.13mm, while the 123R measures 10.17mm, at approximately the same place. How will the 123R burner fit into the same hole as does the 71 burner??????? Inquiring minds want to know!!

Take care, and God Bless!

Every Good Wish,
Doc Mark

 

Hi Doc,
measuring a, that's a bit technical. They do go together nicely though

 

Just a thought Doc, you are presumably measuring the 'male' thread at the inner part of the threads, the depth of the threads would show the 'apparent' difference you seem to have.

 

Hi Doc Mark

You certainly ask some awkward questions.

From 1962 till 1976 Optimus made Optimus and Primus brand liquid fueled stoves. They used the Optimus designs and rebadged some of the stoves as Primus brand with the original Primus numbers. So a Primus 71L without engraving on the tank is actually an Optimus 80 and all parts are interchangeable. The main difference between those made before 1962 is in the tank lid. Primus ones were domed whereas Optimus ones had a slotted top. At some time the slot disappeared and a five sided socket head appeared. This may have been at the time when the dual models started to be made. Hjorth and Bahco made Primus 71Ls have engraved tanks which were produced until 1962. In that year both Bahco and Optimus produced Primus stoves.

I have ever tried it but I should think that the Optimus burners probably fit the genuine 71Ls as often stove parts were interchangeable between makes.

The Optimus made pet80s and 71Ls followed the stove convention in that the tank lid is 45 degrees to the left of the pump except the petrol stoves do not have a pump so use the regulating valve in the pump place. You can nearly always tell if a burner has been replaced because owners do not trust the tapered metal to metal seal so often overtighten the burner which puts the tank lid in the same place often even more than 90 degrees out of position.

Optimus acquired the Svea brand name in 1969 and at that time the burners were identical to the 80s. Any 123 stove with Sievert engraved in the tank cannot be much later than 1969. I do not know for certain whether Optimus also bought parts off Sieverts but in 1962 they definitely acquired Primus parts and continued to make and date code some "Bahco" Primus stoves until 1964. It is possible that some "Sievert" stoves were made by Optimus to use parts that they had acquired.

Optimus changed the burner on the 123 to a burner with an internal cleaning needle and redesignated the stove the 123R however the marking on the tank remained as 123. The threads are identical to the original 123 so the burners are interchangeable at least between 71s, 80s, 123s and 123Rs.

The burners are not interchangeable with Primus 70s which had a tiny burner without a regulating valve. It was a boiling stove without any control of the flame. It also had a handle on the side of the tank. This had an unusual use. You lifted the stove to your face so you could blow the flame out! After that you could release the tank pressure.

Most makes of stoves have interchangable parts. This made sound business sense. If you used the same threads on your stoves you could sell your spare parts to your competitor's customers. If yours were cheaper and available in the same location you could make a killing. Mind I cannot remember Optimus or Primus Spares being really cheap. Some of the British ones undercut them. British 96s use a different thread on the vaporising tubes of their half pint stoves. These will fit Swedish stoves as well as British ones but the Swedish ones will not fit the British ones. The Swedish stoves used Whitworth threads whilst the British ones used UNC threads and a male UNC thread will fit a female Whitworth thread but not the other way around.

Regards Bryan

 

A very interesting reply Bryan, thank you.

 

Wow Brian! You can't buy that kind of information and insight!

Thanks!

CB

 

123R
I should have said this first but i used a 80/71 tank and a 123 burner because i
did not want to take apart my old --first classic--123R to take the burner for the Army #7
if i find another 123R on ebay at a good price--i see them missing parts for cheap--
i'll get one to make the correct swap..

 

The 70's were nice little stove's. The first one's didn't even have a safety 'pin'! It evolved into the 71 eventually even getting a controllable burner as a well as a 'safety 'pin' & loosing it's handle before being renumbered. For a short while Primus sold the old & new style 70 side by side before the 71 took over.

I'm half way through an illustrated article mapping the evolution of the 70-71, which Bryans post has prompted me to read & maybe finish off.

 

Hi

I forgot to mention the problems with the fuel that was experienced by petrol stove users in the UK before the 1970s.This is the main reason that few petrol stoves survive from that period in the UK

Optimus 80s were originally designed for use with unleaded petrol which did not become available in the UK until about the 1970s. When I bought my first 80 in 1958 the instructions clearly stated that the stove should only be used with unleaded petrol. I contacted the supplier who said that the stoves also worked on leaded petrol despite the instructions.

What he forgot to mention was that leaded petrol choked the burners up with the speed of light. I knew nothing about petrol so I assumed that the dearest petrol was the most refined. Wrong assumption! The dearest petrol had more additives in which chokes the burners up even faster! The additives are to prevent preignition in engines. They are effectively fire retardents! I was paying extra to cause myself trouble quicker and probably for my stoves to perform worse!

I think that at some time in the sixties the burners were REPUTEDLY altered so that they could burn leaded petrol. Basically it took them longer to choke up. The only mofication that I can find is that there is a slightly bigger hole coming from the regulating valve on the later burners. The original burners have parallel sides directly below the burner head. Later ones have grooves cut around the burner under the burner head. These may be the leaded petrol burning burners although I have never checked.

If you have a stove with the parallel sided burner it is an early one although that burner was definitely in use until at least 1962. If you have a stove with the grooves under the burner head it is either a one made no sooner than 1962 or the burner has been replaced. On 80s you can usually tell if the burner has been replaced because the tank lid should be 45 degrees to the left of the regulating valve. I do not think that this applies to 123s as I have seen the tank lid on the right of the regulating valves and that has been on stoves that I have believed have been little used. This may have been a mistake or the normal protocol for 123 stoves

If necessary I will take photos to illustrate the differences

Regards Bryan

 

Just for interest a very quick pic of another No 7. Apolgies for the poor setting and lighting.

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Simes

 

SIMES--AND ALL..
thats about where the burner is on mine--unless i get a great deal on a 123R i'll
just live with what i have and not try to get it perfect-- i'm a enthusiast not a collector-
i missed a 123R on ebay this afternoon-there is no way i would pay over $20 for
one without the potholder and cover/pot--
i look forward to some photos of all the different models of this neat little stove

 

Hi Simes

It was nice to see the correct marking on the 7 military stove. I had wondered whether the actual stove was marked 80 but your photo answered the question. Here is my botched up combination.



These were the differences in the pre R burners



These are three of the versions of the ordinary 71s



The one on the left has a plain tank lid. The safety valve is a rod passing through the tank with a solder blob above and below the tank. It is on the right of the tank. The next stage was to provide a domed lidded tank lid with the safety valve in it. This stove is in the centre. It came in a tin marked Bahco so was made between 1955 and 1962. The one on the right is a hybrid. It has an engraved tank which means that it was made by Bahco but it has an Optimus burner head and burner plate, an Optimus tank lid, an Optimus regulating key and came in an Optimus tin with a Paper Primus sticker on it. This means that Optimus acquired some Bahco 71 tanks when they acquired the use of the Primus brand name. I am not certain whether you will be able to see it but the Primus burner plates had a cone shaped depression rather than the concave shaped Optimus ones

There is an oddity in the 71s. There was a model 71E which in theory was a 71 in a set of aluminium pans.



Actually the stove is not a standard 71. It has a smaller tank to reduce the height for fitting into the pans. The stove on the right is the standard 71. The one on the left is the 71E however this is a hybrid. The one on the left is a Bahco made tank, burner, burner head and burner plate but it has an Optimus tank lid on it. It also has a primus paper sticker on it. Obviously another Optimus acquisition at the time they acquired use of the Primus brand name.

Here are the two 80 versions.



The pre 1962 changeover one is on the left. It is nicely engraved but for some odd reason the engraving is on the back of the tank. The later one hasthe sticker on the front. You can see the difference in the tank lids. Early ones had a slotted top. Later ones had the five sided socket top. You can also see the grooves around the top of the burner of the later stove

These are the 123 versions



The one on the left is a Sievert made one. Any one with Sievert on it was made no later than 1969. It has the long Svea key but has had the tank lid changed to a later Optimus one. The windshield of this one is engraved and I think it is an early one. The centre stove is an Optimus made 123 so was made no earlier than 1969. It still has the early plain sided burner which suggests that the grooved burner came in after 1969. The one on the right is a 123R in the process of being restored.

I hope that the photos come through alright as I have been having phot processing trouble lately

Regards Bryan

 

CCS University

Thank you all, great photos and information.

Spudz