Notes from Windward: #63

Wood Gas Conversion

     Most folks don't know that motor vehicles can utilize wood as fuel, but given the recent spike in gasoline prices, I expect that this spring there's going to be a lot of folks taking a fresh look at this old-time technology. Converting one of our rigs to run on wood gas has always been on the "long list" of things I'd like to do here. Now, with gas hitting two dollars a gallon, I'm freshly motivated to move it to the head of my renewable energy project list.

     Our workhorse vehicle for heavy hauling is a 3/4 ton Chevy pickup we bought at the Pine Grove auction some years back. Since then, we've worked it hard and steady, and it's always come through for us. Looks pretty rough, for sure, but it does the job day in and day out, and that's what counts back here in the woods.

     Converting a Chevy 350 engine to run on wood isn't a trivial undertaking, so The Plan is to proceed via a series of steps which would insure that the truck wasn't down for very long at any one time. This is the same way we undertake any large and/or complex project; we break the project down into discrete steps that can be pursued as time and resources allow. It's the process of "take little bites, and chew real well" that insures that we don't bite off too much at any one time, and choke on our ambitions.

     Heinlein phrased it another way when he said that in order to master a task or system that is too large or complex to cope with, tackle the parts that you are able to cope with, and thereby whittle it down to a manageable size.

     Phase One of the conversion project involved rebuilding the truck's running gear.

     It's a tough old truck, but it's got more than 200,000 miles on it, and one goal of the conversion work is to enable it to do keep doing the long runs for years to come.

the passenger side 20 gallon gasoline tank
     And so, while I was recovering from carpal tunnel surgery, the truck went into the shop to have new wheel bearings installed front and back, and with new brakes and new locking hubs, the rolling part of the truck is pretty much as good as new. Indeed, I'd say "better than new" since new trucks just don't have the heavy steel construction and drive train that the older trucks have. For example, most new trucks have belt driven transfer cases that just don't perform under heavy loads like the older, gear to gear transfer cases.

     A lot of the "country vehicles" sold to city folk are more show than substance. I'm thinking of the folks who showed up here a few years back who figured that since they had an SUV, they were prepared for winter in the mountains. It was an underpowered, two-wheel drive pretender, with an automatic transmission no less, but it sure did have a great sound system.

the 20 gallon propane tank ready to install
     Phase Two involves converting the truck to a dual fuel system which can run on either gasoline or propane.

     Wood gas and propane are both delivered to the carbureator as a gas, instead of as a liquid as is gasoline, so this phase of the conversion is focused on getting the engine modified to where it can run off either a liquid fuel or some kind of gaseous fuel such as propane, hydrogen or woodgas. Once that's up and running, we'll address the modifications need to be able to switch between two gaseous fuels: propane and wood gas.

     Chevy work trucks come with two 20 gallon gasoline tanks, one under each side of the truck. The first step in Phase Two involved removing one of the gasoline tanks in order to make room for the 20 gallon propane tank. That was straight forward enough.

     The second step involves mounting a 55" long 20 gallon propane tank up in the space where the secondary gasoline tank used to be, a fairly tedious matter of working it up into place, checking for clearance and the best place to drill the frame for the holes needed to attach the mounting brackets, removing the tank, drilling the frame and then working the tank back into place to check and adjust. Repeat as needed until you get all the mounting holes drilled and everything lines up right.

finished installation
complete with safety chains
     There's nothing much of a challenge about this part other than having to figuring out how to repeatedly jack a hundred pound propane tank up into position under the truck without having it fall on you. It's awkward, but otherwise straight forward enough.

     Once in place, two safety chains were added to secure the tank to the frame in case the mounting bolts should fatigue and break someday. Anytime you do a non-standard installation in a situation subject to vibration and stress, it's a good idea to have a secondary "hold safe" system in place, just in case.

Notes From Windward - Index - Vol. 63