You need to learn how to tune it, since no one else will
know how to!
There are 4 basic parts to a propane system.
1) The tank(pressure vessel). You want a good, NEW tank,or
one with no rust pitts deeper than.025" .The tank MUST be ASME
approved with the clover stamp clearly visible and have the
following: a pressure relief valve,filler valve,bleeder
valve(liquid level gauge), a manual shutoff valve,and a fuel
level gauge(visual) along with a vapor outlet and a liquid
outlet. Automotive propane tanks are very heavy duty,
since tank pressures vary from 40 to as high as 275
psig, depending on ambiant/fuel temp.
2) The Fuel Lock: These valves operate by vacuum, engine
oil pressure or electrical solenoid.
3) The Vaporizer/Regulator: Also called a converter this
little bugger converts high pressure liquid propane into low
4) The Air/Fuel Mixer: This is a very simple carburetor
that mixes air and fuel into the engine. There are three basic
types: air valve mixer,the venturi principal mixer,and the
mechanical metering mixer.
Of course you will also need fuel line to run from the tank
to the fuel lock as well. You need to use triple steel braided
line that can easily handle the high pressure, minimum 250
psi. Also a must is a Hydrostatic Relief valve in line
between any shut-off valves.
Where can you find all of these things? The easiest place
is your local propane supplier. Places like Amerigas, or
Suburban Propane can supply you with all new parts needed for
the conversion. For everything new, you are looking at about
$800. Or you can find the stuff used. I got all of my stuff
from a friend's wrecked propane truck for free. :) The first
step is figuring out where and how to mount your tank. Now
remember, this tank is pressurized, at about 200psi. You
really want to make sure it's in a protected area, and safe
from rocks. If you are going to mount it underneath your rig,
build a very stout skid plate for it! For ease of installation
and for safety's sake, I decided to mount it inside the
vehicle. For added piece of mind, it was securely mounted
completely to the vehicle's roll cage. The tank has a Excess
Flow valve built into the liquid line valve. This will
automatically stop the flow of fuel should a sudden
burst in a line occur.
Now that you have the tank mounted, you can begin mounting
the fuel lock and the regulator/ vaporizor. You want these to
be as close as possible to the carburetor. I mounted mine on
the firewall. The vaporizor needs to have your heater hoses
plumbed into it. The heat from the coolant keeps the propane
nice and warm. If you didn't run coolant through the
vaporizor, it would freeze up after a few minutes. You should
also have the regulator mounted right next to the vaporizor.
Once you have the regulator and vaporizor mounted securely,
you can run the high pressure line from the tank to the
regulator. Be sure to route it so that it is out of harms way.
Keep it away from the exhaust, and away from rocks!
Now that you have the tank, fuel lock and the vaporizor/
regulaor hooked up and mounted, you can install the
carburetor. For me, this was a simple swap out. My propane
carb matched my previous quadrajet exactly, so I simply
removed the old Carburetor, and bolted the propane carb on.
The linkage hooked up the same too. No need for a choke
anymore, either. :)
All that's needed to connect the vaporizor to the
carburetor is some fuel filler line (see
photo). Again, make this line as short as possible, due to
the low pressure.
Now that you have everything hooked up, you can remove some
of your old stuff. You no longer need your gas tank (duh). You
also need to remove your fuel pump, if you have a mechanical
one. If you don't want to make a plate to cover the hole, you
can leave the fuel pump in place. However, you should remove
the push rod that goes from the cam to the pump, since the
pump will no longer need to pump. :)
Now you are ready to fire it up, assuming you have propane
in the tank. If not, trailer it over to the local gas station,
and sit back while they fill up your rig for you. Yep, you get
free full service.
You are now ready to fire it up, and see what happens. When I finished installing my setup for the first time, it was about 20*F and snowing. I turned the key, and it immediately fired up. It idled prefectly smooth, like it had been warmed up for an hour before hand. I was very impressed.
After getting everything setup the way you want, it is recommended that you take your vehicle to a shop that specializes in propane systems for fine tuning. Once again, your local propane supplier should be able to refer you to someone.
Here are some technical specs for LPG:
Weight per gallon:
Boiling point (atmospheric):
per cubic foot (vapor): 2516 BTU
per pound (liquid): 21,591 BTU
per gallon (liquid): 91,547 BTU
Maximum flame temperature:
Ideal combustion ratio:
By weight: 15.5:1
By volume: 24:1
Cubic feet of vapor:
per gallon: 36.4 cu. ft.
per pound: 8.6 cu. ft.