That’s interesting. Kind of confirms my observations.
When my manual mixing is set rich the motor runs just fine at idle but runs rough when reving.
At a lean setting it runs ok at high rpm but skips a few beats at idle.
I would rather have expected the opposite - the gasifier being more restrictive at high demand.
I sure wish Max Gasman was on here to hear these posts. He tried so hard to get it implemented and quite frankly I think most of felt it was unnecessary at the time. Now that a couple have tried it I can see more people working on it. TomC
So, one question I still need to ask is when first setting the auto mixer up, when the membrane is at rest in the center and the engine is not running, is the connection to the air valve set so the air valve is open approximately where it would be when running?
Thank you Kristijan and @gasman Max . What both of you have stated is confirmation of what I have been battling with. At curtain throttle positions I have this rock solid reading in the rich zone, and then at other positions my air/fuel ratio meter will hunt back and forth from rich to lean.
I think I have found the problem, it is in my linkage rod that is hooked up to the air control valve control lever. It has some play in the linkage probably from wear of being used in its opration. I need to fix this. I have been putting the focuse on my cable linkage between the 2 throttle bodies thinking they were not in sync. with each other.
I think if I can tighten up the play in the linkage it will operate the way @Chris built it to work.
Then I will have a solid 1.0 air to 1.1 gas ratio and not something less at times and then more at times.
Then I will be able to add just enough ait from my 3/4" air valve to the mixing chamber to achieve the 1.0 to 1.0 ratio and the auto mixer will do the fine tuning adjustments to keep it there at idle or full throttle and everything in between going down the road.
I think my SWEM, just might get a little bigger in the near future of DOW. I better go buy me a bag of lemons. Yup I am thinking positive in this. It makes no sense to think negative.
Bob
Hi Kristijan
will you show us your new symmetrical pipe system? I would like to understand why the valve in “t” did not work. It seemed cool though!
Hi Jo
can it be that at very high velocity gases in the gas generator the coal bed rises slightly and comes less restrictive, by the very fact?
The opposite may happen, at very low speed, the coal bed closes and the restriction increases?
I for one am going to miss Max, ever so much, if he doesn’t reappear. My hat is off to him.
So wuld l. But when you trink about it, it makes sence. At low gas/air demand the partly open air valve is not realy that restrtictive and the engine will rather suck from it thain from the restrictive gasifier. At high demand its hard to suck on the valve and the mixture richens.
Don, yes it more of less stays put. But as soon as there is a vacuum change its gonna start moving.
Thierry, actualy l dont have the symetrical system! I fixed leaks and some other problem and the automixer works just fine with a T. Its not ideal but it works.
Hi Thierry,
I belive @KristijanL answered the question.
But still, intense heat restricts the charbed. That is obvious, watching the vacuum ratio increase when pulling harder. Apparently the small airvalve gap restriction has an even steeper curve.
Flows and turbulence effects are hard to calculate. Too many input variables. Just add wood and SWEM 
Yes , What JO said 
What JO sayd on turbolency. Specialy our trusted butterfly valves, its funny most of us use them yet they are the worst for the job we intend them for. Idealy we want a linear curve valve, meaning 10% opening allso increases 10% air flow. But the buterfly valves are far from that. Ball valves are slightly better, gate valves even better.
Early in my build, i was playing with a cone valve to achieve a more linear flow adjustment. I just couldnt fit it into the space i wanted it.
I use gate valves whenever possible. Please educate me about cone valves or other more linear options.
I talked to one of our experts at work a while back, he sayd one of the best designs is a type of a ball valve with a V opening in the ball instead of a round hole. Thats how he described it, l havent seen it in person. But for a DIY way l think a gate valve is your best bet.
Some update. I had a problem with the filter sack lately, the support cage in the sack collapsed and it shut off more thain half the sack, engine strugled to draw trugh it. I fixed it and cleaned the entire system, then went to work. Fast startup, but then the system run WAY too rich. I thod the reason is the automixer opened 100% and since the system is fresh and breathable, the opening in the valve is too small. But no, the plunger valve was allmost closed! What is going on???
Anyway, l had to drive on manual.
Hi Kristijan, if your air control valve or plunger valve was almost closed, I would be looking for a air leak on vaccum side of the canister that would pull the valve open. Also make sure the valve is not hanging up when it is operating on char/wood gas.
Can you show us some pictures of how you have the two vaccum lines off the canister hooked up to your air pipe line and char/wood gas pipe line going into your throttle body, to give us a better understanding on how it works?
My auto mixer air valve is piped into a separate twin port throttle body with the other side having the wood gas piped in, and both with a butterfly valves just ahead of it, controlling the volume of air/ gas flow equality. They have equal passage way openings to achieve this.
Bob
Bruce, I just made a cone shaped slug that would slide into a round opening to vary the open area. Here is a copy of the page from my scrapbook where I plotted out the shape. In actual practice I just made a smooth flat sided cone that was close enough.
Also kristijans mention of a b
p.o.
I wish I had that feature on my truck.
If anyone is going to figure out the simplest way to do this auto mixer set up and make it work flawlessly, it will be You Kristijan.
Bob
Hi,
have you cosidered a “semi-auto-mixer”?
This was very often used in the WW2 systems.
Instead of regulating the air completely manually, the air valve was connected to the throttle. If the throttle was closed, the air valve was also nearly closed, if the throttle was opene, the air valve was open as well.
So the proprtions were closer to the ideal over a wide range.
But of course not ideal, so there was a second air valve which was controlled by the driver.
It was set for best power at full throttle and only controlled from time to time. So for WOT, there was best mixture and the link of the air valve to the throttle regulated the mixture for anything less than full throttle.
For sure not absolutely perfect, but since for only a partly pressed pedal not full power is needed a slightly off mixture is still ok.
Gives good results with a much less complicated mechanism than the autmixer, also less likely to have failures due to the membrane.
Have a look at the swedish book, if I remember right a good example is the Hesselmann mixer.
The Gohin-Poulenc as well, there are some pictures here: Admission d'air par tuyères
This just came to my mind as Kristijan and JO as well as Bruce and probably some other use air valves which are not linked to the throttle.
Maybe this can help to improve the mixer without going the full way to the automixer.
Kind regards,
Til
In the first picture ( drawing ) this appears to be an “up” draft mixer. Then the picture of it on an engine it looks like a “down” draft and everything is upside down and backwards to the first drawing. TomC
Huge thanks for this link for gas mixers. But I think we the automixer is VERY simple as Max conceived it and Chris S built it, and now Kristijan has made it even simpler by having it control a gate valve.
Rindert
