Propane Conversion: How to Make LPG Cars

Liquid propane can be a low-emissions alternative fuel for cars. With the right vehicle and know-how, you can have a natural gas car.

| May/June 1972

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    Liquid propane is a tried and tested low-emission fuel.
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    The photos shown here and in the next image in the Gallery illustrate a dual-fuel conversion made to the personal car of James Couillard, Editor of LP-GAS Magazine. The automobile is a 1966 Chevrolet Impala with a 283 cu. in. V-8 engine. Bud Eggen, Northern Propane Gas Company's carburetion specialist in Alexandria, Minnesota — assisted by Harlam Dreger — performed the job in less than four hours. The feature from which this sequence is taken originally appeared in the May, 1970 issue of LP-GAS and has been taken from an IMPCO reprint at the suggestion of Walter Blouch.1. Plan location of all component parts. Use convertor and fuel filter lockoff mounting bracket ( ->) ifossible, for neatness and stability. Note that the carburetor adapter( -> ) is mounted directly on the original gasoline carburetor. Only the air cleaner assembly has been replaced. 2. When planning water line installation, use separate openings on heads and water pump to keep separate from car heater. If this is not possible, tee into heater lines close to block. Eggen used black iron tees. 3. Tighten screws on convertor, fuel filter lockoff and carburetor before installation. This procedure could well eliminate a later service call or a dissatisfied customer. 4. Always mount the convertor ( -> ) in an upright position. It should be as close as possible to the carburetor ( -> ) thereby keeping the vapor hose short. 5, 6. Push lock hose fittings are used for appearance, durability and ease of installation. 7, 8, 9, 10. When measuring and installing water lines, make sure hot water from thermostat side of engine is going to lowest convertor water opening ( -> ) and line from pump suction side of the water pump is going to the convertor's highest opening ( -> ). 11. Note neat appearance of water line installation by using push lock fittings and hose.
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    12. The gasoline fuel lock ( -> ) is installed between the gasoline fuel line and the carburetor. 13. Overview of dual-fuel conversion through the water lines and lockoff installation stage. 14. The top of the Imperial mixer and air cleaner is removed so mixer can be installed on adapter. 15. A Boden choke wire is connected to the mixer. It is used to open the mixer to allow for increased intake of air when the engine is operating on gasoline. 16. Imperial mixer installed on carburetor. 17. The conversion under the hood is completed with the installation of the liquid hose to the fuel filter lockoff, the vapor hose ( -> ) and electrical wiring. 18. In this particular vehicle, the spare tire brackets in the trunk had to be removed. Special attention should be given passenger cars having rearwindow defrosters ( -> ) or rear-radio speakers. They should be sealed or removed. If a manifolded tank arrangement is installed, the "hidden" tank should be ordered smaller to accommodate defrosters or speakers. 19. All tank fittings must be checked and tightened before tank is installed. Special attention to small Allen wrench pipe plugs (-> ) should be given as some have been leakers. 20. The including of an electric fuel gauge as part of passenger car installations is recommended. Electrical wiring in trunk spaces should be positioned out of the way so as not to become easily snagged. The wire connection to the repeater gauge mounted on the dash can be placed under the vehicle's floor carpets to make a neater installation. 21. Stainless steel wire braid hose( -> ) is recommended for fuel lines on all propane carburetion installations. Optional equipment installed on a motor fuel tank can include a vapor takeoff valve ( -> ) so the tank can be used to fuel portable LP-gas burning appliances.

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It works. New York, Maine, Tennessee, Florida, Arkansas, Texas, Utah, California . . . I've traveled miles and miles and miles in a VW bus converted to run on LP (liquid propane) and the easy-to-install system really does result in lower operating and maintenance costs, much longer engine life AND 70% less air pollution.

(Note from the editors: This conversion is for non-fuel-injected vehicles.)  

Unlike gasoline, LP (and from here on, whenever I say LP you can take it to mean liquid propane, homemade methane or natural gas . . . the system will work on any of these) enters your engine as a completely vaporized fuel that's free from lead, carbon, gum, sulfur and most pollutants. LP won't foul your car's plugs, ruin its valves, contaminate its oil, wash down its cylinder walls and rings, burn out its muffler . . . OR destroy the air we all breathe. And while mileage and performance are about the same as with gasoline, cost per gallon of LP generally runs about 15% less than you've probably been paying for fuel.

So what are the disadvantages of this low-polluting system? First, it'll cost you something over $100 (including everything) to do your conversion . . . a bit of money even when you consider that the equipment will transfer readily to your next vehicle. Second, filling up an LP tank simply isn't as convenient as stopping at a gasoline station. However, only a few times in 15,000 miles have I found LP so inaccessible that I was forced to use the other half of my dual system and switch over to gasoline for a while.

There's absolutely nothing new about LP conversion. Excellent equipment of the kind I'm using has been around for over 40 years and more than 250,000 vehicles-mostly trucks, cabs and forklifts—are currently operating on LP. The hardware is well proven.


You'll need five major pieces of equipment to convert your car to LP. All are available from most any LP dealer (with a little help from a hardware store on fittings), although you might want to try getting a used tank from one of the large forklift users or any of the businesses listed under "Gas, Liquified Petroleum, Bulk". If necessary, write to National LP Gas Association, for help in locating equipment dealers near you. OK. Here's what you'll need:

1/24/2014 8:54:36 AM

I was really on the verge of giving up on deciding about using propane conversions but I think somehow I found the answer. I am a newbie here but I would just like to share my experience since some people might feel the same way. At first I was a bit doubtful if converting gas to propane would really fit my expectations but I've come to realized that yes, it is the answer for my longing prayers. It's very affordable, convenient and is truly a lifesaver. I don't need to spend too much on gasoline and I enjoy the perks of saving my precious time and energy. Just to share, try visiting this website that I found, It's a good reference for your concerns about propane conversions. I hope it will help you like it did for me. :)

Mark Villar
2/23/2013 6:12:27 AM

Has anyone ever thought of running their car with water? I have a post on some tips and information you might be interested in.

Robert Bruce
11/23/2012 11:10:47 PM

does anyone know where I can get info on converting an injection car to LP

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