I just picked up an Optimus No7 camp stove at an estate sale for $5.00. Any information on this unit would be appreciated. Looks like everything is there except the trivet. The fuel cap looks different then the few examples I see here. On the top of the cap is flat with a slot and it says Sweden on both sides of the slot. The thumb screw for pressure relief is also marked Sweden on both sides. What years were they produced? Did I do well for $5.00?
Welcome to CCS @junkman Does your stove look like this (but without the trivet as you say)? All I know about the No.7 is in the Stove Reference Gallery section HERE and I suggest you have a read of the entries for the examples there. Five dollars was no rip-off. John
Everything except for the fuel cap.It is flat across the top with a rounded slot.Like a coin could be used to turn the cap.Are model 7's rare?I could find very little information on the model 7 on the internet.
Hi @junkman 1. At $5 you got a real bargain. The regulated burner part alone could be worth more than 10x that amount. 2. The Optimus No.7 was made by adding a regulated silent burner to the same tank as used for an Optimus No.5 (but re-badged as a No.7). Later Optimus just used the No. 5 tank, marked as such, but now called the stove an Optimus 5R (for Regulated) 3. The Optimus No 7 and Optimus No.5R stoves are relatively rare. There were probably hundreds or more plain Optimus No.5 stoves sold for every No.7 or No.5R model. 4. When Optimus took over the liquid fuel stove production of Primus, in the early 1960s, they introduced a Primus No.5R model (the tank is just marked Primus No.5 but an Optimus designed regulated burner is fitted). This Pr. No. 5R is essentially a re-branded Optimus No. 5R. https://classiccampstoves.com/threads/primus-no-5r-late-1960s.23193/ 5. The majority of No.7/No. 5R stoves shown in the stove reference gallery are fitted with a filler cap which incorporates a pressure safety release valve (SRV) which opens at a pre-set pressure level to prevent over-pressurisation of the tank. From your description, your Op. No.7 stove has a plain filler cap, without integral SRV. 6. The plain slotted cap you describe (photos would be helpful) sounds like a type of filler cap used on both Optimus and Primus branded stoves in the late 1960s - 1980s so could be a later addition as I believe that your Op.No.7 stove was likely manufactured in the late 1950s/ early 1960s. https://classiccampstoves.com/threads/primus-no-1-1960s.7282/ 7. The SWEDEN SWEDEN markings of the air release thumb screw and filler cap also suggest a post Primus Trading Co. date (early 1960s) as this simple marking allowed the same thumb screw and filler to be used on both Optimus and Primus branded stoves. Trust this helps. Best Regards, Kerophile.
Very nice explanation @kerophile. Thanks for taking the time to help a noobie out and educate me in the process. Ben
Thank you.I'm new to this.my only experience with this sort of thing is old Coleman lanterns and stoves.Old Coleman lanterns always had the year stamped on the bottom of the tank.So they were always pretty easy to identify.
Is there any place I could find the trivet that fits this stove?I'm assuming that a model 5 would fit.
Hi, generic trivets are available and any intended for a two-pint capacity stove, such as a No.1 of No.5 type should fit. Trivets generally would have the manufacturers name and country of origin but not a stove model number, which is useful when seeking a replacment. As to a source of suitable parts: Look for bella10202 on ebay. Best Regards, Kerophile.
Thanks for pointing me in the right direction.I plan on using this stove for camping.It takes up a lot less room than my current stove.It's a single burner propane unit for a fish fryer.i really like the idea of not having to lug around a 25 pound bottle of propane.Space is pretty limited in my vehicle being that it is a Jeep Wrangler.
Hi @junkman . Please be aware that this stove is intended for kerosene fuel. Under no circustances should Coleman fuel or gasolene be used in it as this could be very dangerous. Enjoy your stove it is a great unit. Best Regards, Kerophile.
Seems to be a slight learning curve to lighting this up.Took me three attempts before I got it.And my wife kept asking me to move farther away from the house.
Actually it is sound advice with any new stove. A recent post about a fuel leak had fuel spread all over the work area and had it not gone out quickly it might have been a lot worse.
Once I figured it out it fired rite up and burned with a nice blue flame.It burned on full blast for a few hours before I shut it down.
Attempt number one resulted in a three foot flame that was out of control until I shut the valve off.Number two was not so dramatic.And number three I finally got it.
Hi @junkman Sorry that you initially had flaring problems with your Primus No.7 The thing to remember with any kerosene burner, and particularly a silent model, is that the priming stage only heats the burner sufficiently to get it started. The full operating temperature is not achieved until the burner has been running for a few minutes, when you can then increase tank pressure to achieve higher power. If you start with too high a tank pressure, or open the regulator valve too wide, you can flood the vaporiser with liquid kerosene, get liquid coming through the jet, and quench the previously hot metal of the vaporiser. The result is a flare up of liquid kerosene with copious yellow (fuel-rich) flames. All you can then do is shut off the fuel, re-prime, and start all over again. Best Regards, Kerophile.
I was just messing around out in the shop and figured priming heat is heat no matter what the method.So I gently warmed the burner and generator tube with a propane torch and it worked great.Anybody else ever try this method?Or is this a big no no
@junkman An effective way of making sure your spirits prime properly is to put a wick or carbon felt in the priming cup. Fill the cup; let it all burn. Cheers Tony
