PLATED CASED OPTIMUS 8

Discussion in 'Optimus No:8 (version prior to the 8R)' started by kaw550red, Mar 8, 2009.

  1. kaw550red

    kaw550red RIP

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    Optimus applied for the patent for this type of stove on 28 September, 1927. I do not know the patent period at that time however I think that at present it is 20 years. This case is NOT marked with the patent number so must have been made after 28 September 1947.

    However petrol was rationed in the 1940s and the only private individuals fortunate enough to get a ration owned cars and they were unlikely to have wasted petrol on a stove so there would have been little point in selling an unusable stove in this country during petrol rationing. The 8 was superseded by the 8R in the middle 1950s and most of the pre 8R stoves are in painted rounded corner boxes which are much more common than this shaped case. It appears that the stove was probably made around 1950 and was probably amongst the first sold in this country when we started importing Swedish stoves again

    That type of tank lid was in use on stoves in the 1950s until at least 1962. The lid is nickel plated so is likely to be original

    1236520784-No_8_open_opt.jpg 1236520821-No_8_case_opt.jpg

    The case may look the same as the aluminium cased 8 but it is not. This one is definitely plated steel. I have no idea what the plating is but it discolours to a dark grey like tarnished aluminium
     
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  2. Bom Bom Bom Bom

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    Hi Bryan,

    If I recall correctly the burner arrangement on this model different to other 8s/8Rs.

    On the model I own the burner screws onto an elbow joint on the feed tube from the tank. The other end of the feed tube is permanently soldered into the tank.

    My version runs significantly below optimum. I very strongly suspect this is due to the wick which appears to be in very poor state with little of it protruding into the tank. Plus it's the only component I've not yet fettled!

    Your vast experience of stoves might assist in answering this question. The feed tube is permanently affixed to the tank at one end, and the other end has a 90 degree elbow joint. Do you have any clues, tips, or hints as to how the heck you can get at the wick to replace it without resorting to unsoldering the feed tube at either the tank end or the elbow joint end?

    This has been driving me mad for ages :-k ](*,)
     
  3. kaw550red

    kaw550red RIP

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    Hi Graham

    Sorry I have just come across your query as I forgot to subscribe to the post.

    I do not have any 8s left so cannot check the connection to the tank and much of the following comments only apply if you can unscrew the burner from the tank

    The wick of petrol stoves get a lot of blame that it does not deserve. I have seldom found that the wick was the problem on a petrol stove. On an 8 the fuel outlet for the burner comes out part of the way up the tank so there are times when the fuel level is below the outlet. The wick hangs down into that fuel and draws up the fuel up so that tank pressure blows it into the burner. I suspect that the wick also acts as a filter resisting muck which would otherwise get to the burner.

    Petrol stoves were designed for unleaded petrol which was not available in the UK until about 1970. The 8s went out of production in 1955 so any 8 must have been run on leaded petrol. This contained additives which choked the burners up so a lot of petrol stoves from that period were thrown out when the stopped working through choked burners.

    You need to clean the inside of the burner to remove the choking deposits from the leaded petrol.

    Unscrew the burner from the tank, remove the wick, nipple and regulating spindle.

    You need a bucket of water, a blowlamp and a stiff rod like a long stove leg.

    Support the burner on the rod (I put the rod in the regulating valve hole), heat it red hot and drop it in the bucket of water. Black particles should shoot out of the burner into the water.

    Make sure that the ends of the burner do not face you when you put it in the water as boiling water is ejected from the ends and you could get scalded if an open end faced you

    Empty the water and repeat until no particles come out of the burner when quenched in the water. You empty the water so that you can see when no more particles come out when quenched.

    If you can connect a mains hose to the burner after quenching the water flowing through the burner will force some of the deposits out and that will speed things up. I have adaptors for this and it will not be easy without them.

    Reassemble the burner, fit to the tank and fit a new nipple if possible.

    Your stove should now work properly.

    This cleaning method works partly by burning the deposits out of the burner and partly by thermal shock. Quenching the burner in cold water causes the metal to shrink rapidly. The deposits in the burner shrinks less quickly that the metal so you get a stress between the metal and deposits and this cracks the deposits off the metal.

    The additives in vehicle petrol are partly to protect the valve seats in engines and partly to prevent preignition before the sparking plug ignites the fuel at the correct time. I think that the additives to prevent preignition are effectively fire extinguishing chemicals so it is not a good idea to use vehicle petrol in stoves for practical reasons as well as health reasons

    My 80s cost me a fortune for replacement burners until I discovered this method of cleaning them. It has a very high success rate although sometimes burners can refuse to clear if they are really bad.

    If your burner is definitely permanently fixed to the tank I cannot think of any practical and safe way to clean the burner. However the 8s are very collectable as few survive due to the choking action of leaded petrol

    Good luck.

    Regards Bryan
     
  4. Rick b

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    Hi Bryan, Thanks for the information on cleaning out burners. I have read other posts, but now I finally get it.
     
  5. Bom Bom Bom Bom

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    Hi Bryan,

    Thanks for the detailed explanation. However, it's not quite covering the question I had! I feel some pictures are required so I'll take some and post the query in the fettling forum.
     
  6. Spiritburner

    Spiritburner Admin SotM Winner Subscriber

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    Graham - I may have a spare tank which may have a good wick. I'll check later it is the one you refer too.

    I just fettled an old Pifco petrol stove yesterday - changing the wick turned it from a candle to a proper roarer. (pics in the relevant section to follow).
     
  7. kaw550red

    kaw550red RIP

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    Hi Ross, Graham

    I started using petrol stoves in 1958 but until recently have never had to change a wick as such. I recently had to change one because the old one was falling apart.

    Howevert in the period when I used the stoves a lot I regularly changed the burners which included the wick so my experience may be misleading.

    My main problem was choked burners through having to use car petrol so I automatically think of that if I cannot get a petrol stove to give its proper performance.

    Recently I came across a petrol stove that had a scorched wick. It worked okay but I tried to work out what effect the carbonized cotton would have. When the fuel level is low the wick pulls up the fuel from the bottom of the tank by capillary attraction. I do not think that the carbonizing would have any effect on capillary attraction but it then occurred to me that the carbonized cotton would be brittle and particles could break off. Pressure within the tank would force these particles into the fuel tube which is packed with compressed wick and that could choke the wick and prevent the fuel getting to the burner.

    It may be that I have been lucky in not experiencing wick troubles however if dirty fuel was used in a stove or a stove was used with a carbonized wick that the filtering action of the wick in the fuel tube would collect small particles and eventually prevent a proper flow of fuel to the burner.

    I get concerned that the wick gets automatically blamed for any burning problems. I know of one collector who blamed the wick for problems with a 111 model that was not even fitted with a wick.

    Regards Bryan
     
  8. Bom Bom Bom Bom

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    Hi Bryan,

    Thanks for your usual valuable insights. I also rarely have had cause to change wicks but occasionally they are so clogged it's the only recourse. I believe this is the case with my example of this stove. However, how to change the wick on this stove has proved to be beyond my ability to work out how to do it. I've made a post with pictures in the fettling forum here to continue the discussion.
     
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