Alcohol Fuel Powers this Experimental Truck
(Page 2 of 8)
September/October 1979
The Mother Earth News editors
When the carburetor is completely free from all external attachments, remove it from the manifold. (Single-barrel units usually have only two fastening nuts or bolts, while two- or four-barrel models use four-point mounts. Once the carburetor is off the engine, drain the gasoline from it by turning it upside down, and—if it's covered with grime—take the time to clean the assembly off with an automotive degreasing solvent (but not a carburetor cleaner, which would deteriorate rubber parts).
RELATED CONTENT
MOTHER'S ALCOHOL ROAD SHOW May/June 1980 Here's the latest word on our traveling ethanol fuel semin...
A 50-STATE ACCESS GUIDE TO ALCOHOL FUEL LAWS November/December 1980 Here's the latest report in MOT...
New research from the Environmental Law Institute shows that, from 2002 to 2008, the federal govern...
Rock Port, Mo., took advantage of the power generated from the nearby Loess Hills Wind Farm in a bi...
The recent wave of information about climate change, fossil fuel dependence and the ubiquitous pres...
A "BORING" EXPLANATION
In order to use alcohol fuel in an engine designed to burn gasoline, it's necessary to enlarge the opening in the carburetor's main jet (or jets, if your carb is a multithroat model). Start by removing the air horn from the float bowl as in Photo 1. In most cases there will be a choke stepdown linkage rod—and possibly some other mechanical connection—between the two components. Disconnect these, if you can, before unthreading the air horn's fastening screws.
Next, locate the main jet (Photo 2). Some carburetors—such as the unit pictured—have the jet installed in a main well support (a towerlike mount fastened to the air horn), while others mount the metering device directly in the float bowl body. In any case, you shouldn't have any trouble identifying the removable main jet: It's a round brass fitting—with a hole in its center and a slot in its top—that threads into place.
Now remove the float assembly, unscrew the jet, and measure the diameter of its central orifice. The simplest way to do this is to find a drill bit that fits snugly into the hole, then determine the size of the bit by matching its drill number to its diameter—in thousandths of an inch—using a conversion chart available at your local hardware store or in a machinist's handbook. (You can also use a micrometer to figure the drill size.)
Once you've determined the "normal" size of your gasoline jet's orifice, prepare to increase that dimension by about 40%a· Remember that this isn't a fixed percentage for every engine ... you might have. to drill several different jets—in progressive increments above and below that figure—and try them out (by actually running the vehicle) to see how they work.
For example, MOTHER's six-cylinder truck uses a .056" main jet to operate on gasoline. By enlarging the hole 40% (to .0784') with a No. 47 drill, we made the opening just about right (in fact, that increase was almost perfect on our particular vehicle) for alcohol fuel. If the orifice is too small, it won't allow enough liquid to, enter the system . . . and the engine will backfire and miss. (It may also burn valves if left in such a lean condition for an extended period of time.) On the other hand, if the jet is over-enlarged, the mixture will be too rich and you'll waste fuel.
Be sure to hold the jet with vise-grips while you carefully bore out its central hole and, if possible, use part of the carburetor itself as a "mount" when you drill . . . as in Photo 3. (If you do this, be sure to clean any brass residue out of the carburetor and its components.)
Page:
<< Previous 1 | 2 |
3 |
4 |
5 |
6 |
7 |
8 |
Next >>
