Mixing valve

How do I address this group? Fellow Gasifists?
Next week I will begin installing my gasifier on a 1970 dodge power wagon with a 360 cid. A friend of mine is letting me experiment on his old truck for a month, runs well but has cancer real bad. If I can make this work with a measure of success then I will be “ALL IN” with respect to wood gas on a vehicle. From what I understand and everything I have read you need to have a one to one ratio of wood gas to air entering the engine for it to run. That means you need a mixing valve to fine tune the ratio. I see some have used a choke cable from within the cab so as to adjust on the fly. A ball valve wont work on a choke cable and commercial butterfly valves dont look like they would work either. I have a flapper valve design that I was going to have built by a machine shop but before I spend a wad of money I thought I would ask what everyone one else is doing under the hood. What about idle speed and mixture? If you get a 1 to 1 mix at idle how do you maintain that ratio on up through passing gear? It would seem that you cant have both extremes because of pressure differentials and flow through a fixed orifice. Has anyone worked on a modulating valve to maintain a ratio balance at any pressure? Lastly, it seems that many ppl like to use older trucks. If this experiment works for me then I’m off to buy a V8 truck and sell my F250 powerstroke but up here things rust fast so old is out of the question. What about a performance chip that would advance engine timing? How do the oxygen sensors respond to the wood gas?

All I wanted to do was replace the wood boiler I built back in 94 that heats my house. I was only looking for some new ideas on wood burning and what? gasification, whats that? now you know the rest of the story.

Easiest thing will be a large washer inside a pipe, acting as a butterfly valve. It doesn’t’ need to seal, just acts like a damper.

For the idle, a string tied to the gas pedal will work amazingly well.

Wes, The Construction video #31(on Plumbing) shows Wayne building these valves. (Minutes 2 to about 6.) They are in the Premium section.

Hello Mr. Wes and welcome aboard sir.

I guess all us woodgasers have been addressed in many different ways. Several years back when I was putting my first project together and folks ask what I was doing ,and I said planing on running my trucks on saw mill slabs. With their words , expressions gestures etc. I knew they thought I was an idiot. After this when anyone would ask, I would say I was building a heater.

In your beginning phase of the gasifier you may be looked on as being weird but when completed and your the only guy driving around your town without gasoline they will look on you differently.


The woodgas usually burns good at around a 1 to 1 ratio. To achieve this ratio will depend on the air mix setting and this setting will depend if the gasifier is operating loose or dense.

The restriction in the gasifier when measuring the vacuum before gasification and post gasification should operate in the rage of 2 to 1 and on up to a 4 to 1 ratio.

If I am running a loose gasifier with a ratio of about 2 to 1 I would expect to have the air mixing valves set at about a 3/4 closed . If I were running a dense gasifier 4 to 1 I would need to set the air mix near 7/8 closed .

To achieve the correct mixing of the gas and air we will have to restrict the incoming air quite a lot.

I thank you for your reply. It isn’t everyday you get to correspond with the seasoned experts of wood gas such as yourself. I have seen many of your videos and read much of your articles. Yes, I have a few friends that think I’m a few fries short of a happy meal, but I have twice as many supporting my endeavor. I will prob be the first person in my county to run a vehicle on wood gas. I drive 35 miles one way to work every day and look forward to doing that on wood. In response to your comment on ratio, at first it would seem that the total nozzle size would indicate a loose or dense gasifier but maybe I misunderstand and it is a reference to the fuel size? If that is the case then you might have to adjust the air mix per batch of fuel? Can the ratio’s change during the usage of fuel? I do plan on having pressure gauges and temp measurement in the cab so I can monitor conditions. I’m wondering just how often while driving down the road you have to adjust the air ratio?


Thanks, I like it! You saved me $150.00 having a special valve made. Washer welded to a spindle in a pipe, I can do this!

Where is the premium section?

Don’t mean to sound smart, we all started at the beginning, but yes everything changes all the time. :slight_smile: When wood changes to charcoal, some of it curls up, some just turns black, and some crumbles real fine. The char bed, which is the “breathing element” varies with wood, vibration, and how hard you are pulling. Mine is a little tight this week, that’s part of the other 75% 35 miles is a good run on a gasifier, you’ll save LOTS of gas money. Chris Saenz will set you up to access the premium section.

Thanks Carl for the explanation. This reminds me of having to adjust fuel pressure on a small plane as you change altitude. I have been around engines long enough to know when they are running rich or lean on gasoline. Is it the same engine response when driving with wood gas?

I Have set aside May 17-19 to go to the wood gas meetup. My kids live in Indiana so I’m planning on this event. I’ll register as the time gets closer and when I can make sure I wont be on a job site.

Hi Wes, most folks today don’t have a clue how to adjust fuel mix, let alone a manual choke! Lean and rich is still pretty much the same on wood, but I find a A/F gauge is helpful. Hope you can make Argos, it will be an EVENT!

Hi WesK
Light airplane expereinced? Great. Then you know about manually changing air/fuel ratios, manual ignition timing adjusts and even watching exhaust and maybe cylinder heads temps all the while on the fly to changing conditions.

Woodgas fuel is actually produced in this deep char bed both Wayne and Carl refer to.
The engine must suck the fuel gases out and down through this variable flow restictive changing active hot char bed. Plus suck fuel gases through all of the piping and a filter bed too.
The ratio Wanne is talking about would be the gasifier internal measured “vacumn” versus atmospheric pressure difference between above the char to below the char bed.
It is because of the fuel gases supply char and filter beds created low to the engine pressures versus atmospheric that you must then be able to restict “choke down” the engine in air flow to match available fuel gases flow sucked in. Open, able to flow all air it can will lean out your into the engine cylinders A/F too lean then to combust. Cough. Backfire. And die out.
'Nother way to think of this:
Normally we let an engine suck in all of the air it can and we then control the delivered fuel to match this.
Woogasing you let the engine suck all of the fuel gases it can and then contol the engine air to match this fuel.
Hope this helps.
Steve Unruh