Look at this skizz of Jans gasifier. The domes are great at releafing stress from heat cicles. A 90° weld is more suseptible to cracking. Even worse is rectangular geometry, one of the reason my gasifier fell in batle.
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Four years ago, when I started the Rabbit build, I read someones thread (maybe Sean French???) about welding ss to mild steel being the biggest mistake, due to the different expansion rates. At the time there was a lot of talk about mild steel firetubes flaking in the nozzle area and eventually sagging. Herb Hartman and Carl Zinn started to put protective shielding in. Herb even used thin ss. Also at the time, someone made a domeshaped topplate on his WK (don’t remember who).
I happened to have access to ss tubing and mild steel propane bottles. I did some further investigation about welding ss to mild steel and decided to give it a go, despite the earlier warnings.
I have over 10,000 miles on each gasifier now and no cracking that I know of. I think the domes are what made it possible.
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Hi,Tom
21.8.2019
What i was asking for was: If an improvised (temporal) sucking route could be arranged (just for test-sucking the lid).
As a test setup, besides the normal gas-routing!
I am familiar with your change-over rotary slides.
If that air-flap in the carburetor body (choke-flap) has a smaller spring-closed flap, for modest gasoline enriching, it will SPOIL woodgas mixing!
You need a SOLID air-flap without any “moderator” for gasoline over-enriching!
It will spoil your need of controlling the wood-gas—air ratio!
Dam it! Spoiling a self-cleaning reduction zone instead of asking first!
The char in the reduction zone glows and reduces the glowing CO2 gas.
A well functioning oxidation zone delivers no oxygen! Sneaking lid-air is directed into the nozzle stream with a proper nozzle-cone!
Half-measures bring only half-results, or less!
Max
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That is true on manually blending gasifier systems, but with my auto mixer that mixing 1:1 ratio of air to wood gas, if you have already weak wood gas and blend with 1 to 1 you now have very weak wood gas. This has been a lot of my problems.
Bob
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Where in your build are these domes? I know where the one is in he WK build. And how do the domes play into mild steel fusing to stainless. Point me to the skizz that Kristijan mentioned. You certainly have a good recollection of post that have been made. I wonder how Herb is doing, and Carl Zinn hasn’t been very active lately. TomC
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Hi, Tom!
22.8.2019
It struck me, that you have not presented the new measures, since your radical rebuild!
- Nozzle screwing holes + tip hole diameter
- Nozzle distance = tip to tip! (opposite)
- Inner diameter of heart,
- Height from the horizontal screw-hole center line to restriction surface,
- Restriction diameter,
- Reduction cone diameters (2)
- Reduction cone height
- Grate
Here may the secret of the “brand factory” lie! Start measuring! + lid leak!
Max
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Bob, ofcorse, l forgot to mention that…
Tom, click on the link l posted you will see what we talk about.
Since ss and mild steel have different expansion rates a 90° weld can easyaly crack becouse it has forces on it in all directions. A dome is flexible in all directions.
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Tom, what Kristjan said.
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JO, I guess I didn’t realize the technicalities of your build. I thought you had curved domes in a couple of places was because you used propane tanks that come with the dome. Didn’t dawn on me that you were mixing metals. You seem to like doing things that some might say can’t be done. TomC
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Hey guys, As you may already know, I’m trying to cure ‘‘leaks’’. After a couple of days, I’m still under the hood. I’m sure in the past I have been able to get my air cleaner sealed enough that putting my hand over the airborne would kill the engine. This time, it ain’t happen’n. I have a rubber boot that is suppose to rconnect the air cleaner air horn to the a-filter. It is shaped like an accordion. When I put my hand over the a-filter end, the carb vacuum retracts the ‘‘accordion’’ to it’s shortest length, BUT the engine doesn’t die. The IAC can’t be adding air to keep the engine running can it??? I have the air cleaner almost totally enclose in sylicon. TomC
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Tom, you have to pay attention 
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Hi, Tom!
23.8.2019
Besides the very important leak investigation and repair, the
8 measures in message
1167
makes it likely to pinpoint the malfunctions in the gasifier,
if you want it solved!
Max
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Did you plug the idle air bypass?
Caused me lots of grief, a 1/2 inch hose directly into the manifold under everything
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Hey Michael— I don’t remember seeing such a thing. I’ll gladly check first thing in the morning. I’m running a Chev TB injection. Do you think I have one. Can I see it without taking the TB off the manifold? Thanks for the suggestion. TomC
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Tom, on my chevy, it was made right into the throttle body. Just a passage with a solenoid to operate it. Mine was newer than yours, but maybe a family trait?
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I pushed a piece of wet rag into the iac inlet, like Wayne does. However, it must have come out the other side and the motor swallowed it. Anyway, everything is completly plugged by soot by now, so I’m fine.
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You live under a lucky star!! You do all these things that you aren’t suppose to do, weld stainless to steel, take out the grate, forget to put in a ash clean out, and stuff more than double the nozzles suggested by the old timers and it all works out for you. Now you stuff a rag in a hole and the engine eats it, but it doesn’t matter, the hole filled over with soot. I build right by the numbers and nothing works. I bet when you go fishing the fish jump right into the boat before you get bait on the line. TomC
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I tried blocking it (IAC)on the ranger, wouldn’t idle on gasoline.
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I have got to find this IAC orifice or what ever it is I’m looking for. Never gave a thought that in order for the IAC to work it has to have an air inlet. TomC
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Hey Tom, I got a big laugh out of your lucky star post up above. You must be quite a character. At least you can enjoy other people’s successes. That post is a keeper.
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