You may have seen my post asking about my No.2 stove and the problems of it running rich. Serves me right for buying one you might say! However I do want to get this running right and last night I had another crack at it. Thinking it is getting too much fuel for the available air and having a new spare jet for it, I thought I'd modify the one fitted to the burner. My Omnifuel uses a .37mm jet for petrol so I thought that would be a good place to start. The smallest drills I have are .35mm and .45mm and the jet hole was somewhere in between these, but definitely larger than the .35mm one. I peened the hole smaller and then using the .35mm bit by hand opened it out again. This gave me my cleanest flame yet but I think it could go smaller still so I need to get a .3mm bit to try. The first picture is fully warmed up and on a high setting. Next is one on a lower setting, while the third is the result of bringing the cleaning needle in to use, it appears to have opened the jet up again. Bugger! Lastly is one with the cleaning needle partly blocking the jet, is this how it should look? Simon.
I shudder at seeing those pics when I remember what owning one of those was like. The last pic shows approximately ok combustion but it amounts to a simmer, so I wouldn't aspire to that as the flame to aim for. A giveaway that it's simmering is the way the burner cap's glowing red, which silent burner caps tend to do when the burner's throttled down to a simmer. The peened version on high and medium's still rich, but typical for this burner I'd say, even on an unworn jet.
Not bad but still a tad rich, keep persevering, they are great stoves. With the burner cap glowing red it also indicates a fair bit of underburn, ie the majority of the combustion is happening inside the cap as opposed to on the edge/outside. This is also reducing the efficiency. When you get the mixture tweaked it will be fine Mine on simmer: Full throttle: With its diesel son.... Alec.
Reckon that's about as good as it gets Alec! Well done , and they need to be used often to keep them good. Flash it up regular and enjoy the Compo rations! Steve.
Not had much time to play with the stove any more yet. I have briefly tried peening the hole a little more after using the .35 drill bit and it was slightly better still. Also it appears the jet from a 111 will fit, does anyone know what size the petrol jet from a 111 is? Might be better buying one rather than some .3mm bits. I also discovered that the cleaning needle had a burr on that was responsible for opening up my jet. I'm guessing that it was cut with shears and that left the burr. The needle itself is .27mm and I've now cleaned up the end to remove the burr. Simon.
I've now decided to opt for a burner rebuild along the lines of the one BD did (thanks BD for your post). Reducing the jet seemed to help up to a point, but I felt it wasn't going to have the desired effect and I'd end up with the stove being underpowered. Below are some pics of my burner head after removing it and opening it up. Like BD I used a step drill to remove the centre tube, going in from either side. I then put the head in my lathe and scored a groove in the underside until I could remove the bottom. The burner was stuffed full of wire wool. Hopefully it will all braze back together again easily, just waiting on some brass to make a new centre tube.
Commendable determination! Good for you. It looks pretty clean in there, so not a deep-clean job to put things right, but some way of getting more air in the fuel/air mix and proper combustion I guess? John
It is indeed. I'm attempting to replicate what BD achieved when he worked on these burners. Hopefully I've not just messed up a mostly working stove and it will run better when I'm done! Simon.
Not at all, the pictures are also a valuable reference. Most burners are full of rusty dross, interesting to see inside a good one. Alec
