Video showing what I meant by balanced air flap.
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Chris,
Nice work on the balanced air valve. I’m living vicariously thru your posts since I am committed to finish a long “honey-do” list of house repairs before I can get back into the shop.
I like Max’s idea of threading the rod and using a nut on each side of the diaphram. A nylon bushing to match the rod will allow easy movement thru the chamber wall.
Good to hear that 16" is overkill. Maybe 10" diameter by 3" deep cake pans will do? Much cheaper. With my jigsaw I can cut two 11 inch diameter washers with 10 inch holes from 1/8" thick aluminum sheet to slip over each pan and rest on the opposing rims/lips. By drilling matching holes thru both washers for bolts and nuts around the perimeter the pans can be securely clamped together. This method works well on my wide and shallow charcoal filter.
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I would start by tunning the spark plugs. Not saying it’s correct. That’s just me…
It’s all good stuff,
Jeff
Indeed! When the gasproduction and treatment and
controllable delivery are in order…
If I put the gaps in my Audi to wartime 0,3–0,4 mm,
it will have a remarkably “cracking” sound on low idle.
But as soon as the gaps are put to 0,8 mm and higher,
the sound gets soft as harmonious music!
1,0 mm works perfectly from low idle to WOT working uphill.
Then the “clocking” (turning the flag) with the in-streaming
gas-mix improves the acceleration…
Still the 4-point plugs (Bosch) are on the list…
What experience have you lived through, and what’s comming
up next?
Max
The common recommendation that I’ve found on a number of sites for natural gas and propane is about 20% closer plug gap. That seems to work well on CO. I will start listening for the “cracking” sound.
Bruce
Hi, Bruce!
Closer gap, are you (they) refering to gasoline as a starting point?
I have no reference to gasoline, but the reference in the Audi service book, which is not consulted in this matter yet!
The reference to the “wartime” gap was a reality in those days, with weak ignition coils and bad insulation on all hightension cables, bad condensers in the primary circuits, and you name it…
Accumulators dipping the tensions when cranking made it worse.
DC Dynamos could not keep up with the frequent fanning…
Now in the Audi, I made a series of gap settings from 0,3 mm upwards to 1,0 mm, 0,1 mm at a time.
There was still some “cracking” at 0,6 mm.
The refered sound is exhaust sound.
1.0 mm was giving absolute wonderful sound and power results.
All flags “clocked” in “downwind” to the incomming gas-mix stream!
Max
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Hi Max,
Yes, gap for gasoline as starting point. Nothing beats actual tests with empirical results. Thanks for your test data.
Bruce
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Hi, Bruce!
Drawing a conclusion from this, seems to be:
The richer (heat value) the fuel-mix has, the smaller the gap is used.
Acheived firefront speed seems unimportant in this comparison…
as long as the compression ratio stays under ~14:1.
Gasoline 0,8 – 0,9 mm / woodgas 1,0 mm.
Max
I guess my progression to the smaller gap suggestion for charcoal gas had a few leaps of logic. I first noticed that old charcoal gasifier instructions recommended .012-.015 spark plug gap, then I came across propane and natural gas instructions recommending a narrower gap. Heat value of propane is twice that of natural gas per volume, but 20% narrower gap is recommended for both fuels. I assumed the spark gap had something to do with gaseous fuel vs atomized fuel. Natural gas has over 3 times the heat value of CO per volume. I assume air fuel ratios figure in here somehow so we should compare stoichiometric mixed fuel per volume not just the heat value of fuel gases per volume. Max, hold my hand and lead me through the heat value spark gap issue comparing gasoline to wood gas to CO. How might compression ratio and modern ignition systems affect optimum spark plug gap?
Bruce
Hi, Bruce!
First, those charcoal instructions have a definite “ring” of wartime accumulators and DC dynamos on 6 Volt…
Low compression ratios, little compression heat, damp gas, if not in Australia… …
Right?
Then, you are on it; it is the heat value of the gas mix and not the fuel heat value as free-burning.
High calorie value gas needs much air, low heat value gas needs less air; this reduces the difference of various gas-mixes.
How about this: The less nitrogen in the mix, the larger the spark gap?
See what you find!
Modern ignition systems have modern maintaining systems to keep accumulators well and alive, less susceptible to dip at cranking and failing.
Max
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If you are having trouble sensing the small pressure changes you need and using that “push” to drive a valve:
A $4.00 Arduino Uno, a $10.00 servo and a $14.00 Freescale MPXV7002DP differential pressure sensor will do it easily and reliably.
Pete Stanaitis
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you probably also need a roll of aluminum foil to protect everything from electro magnetic interference from the engine.
I would try the MPXV7007DP instead it has a wider pressure range and higher operating temperature range. Plus I think they might have discontinued the 7002, and they are the same price.
It is too bad the silicon diaphragm versions won’t work.
Yeah you could map the signal to a pot and have full adjustability 
Hi! Pete, Sean, Matt.
Yes, if sensitivity gets you sole! Now a full regulation range within 0.5" WC is good enough for proper and smooth operation. Why then expand the range of service needs with electronic gadgets?
If you start without any electricity available where is the advancement?
By the way, start up does not need any prebalancing for minute intake flows; the twin-flap dispensing makes that with help of the sucking vacuum… INSTANTLY!
Max
Looks great Chris! Those bearings will probably never wear out.
Mr. Max.
I’m trying the mechanical approach first for a couple of reasons but I still believe it will work with the electronics. Without the electronics our engines won’t start anyway.
It is possible to build an engine with minimum of electronics. May not be legal for the road but I wouldn’t tell if you don’t.
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You don’t need ANY electronics.
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Hi, Arvid!
Stationary- and small boatmotors run excellently with magneto ignition. So does many tractors too… with the “sportsman” handcranking.
Needs to master the mixing ratio at very low flows, which means precision twin flaps for dispensing.
Additionally, a small manifold vacuum bellow, diaphragm or cylinder to do the flap opening overcomming a spiral when reaching a preset vacuum.
Handgas setting only restricts how much the twin flaps are allowed to open!
This way the precondition of gas flow by gasifier overpressure or ventilating does not affect the desired mixing ratio by the twin flaps!
Otherwise, no problems, besides manual ventilation.
Gas mixing (dry) does not need electrical gadgets.
Max
Here’s a few important sounding questions from a newbie with no experience: doesn’t the woodgas from the reactor vary in “strength/quality” as well as “amount/quantity”? I.e. Weak gas after coasting down a long hill would have a different fuel/energy density, even if it has the same vacuum/water-column and cubic-volume-per-minute flow rate of gas, as richer gas from a gasifier running at peak temperatures/flows? Wouldn’t that inherent difference in fuel/energy density of the gas, which is not directly tied to gasifier vacuum/flow, cause discrepancies in the fuel/air ratio, needing adjustment?
Would a pressure-differential mixer such as this be able to account for that needed adjustment?
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