Converting Gasoline to Propane
Many people have asked why would you convert a perfectly good gasoline engine over to propane? I must admit, that is a good question. The main driving force behind this conversion is to take the issues with a carburetor completely out of the picture. Do not get me wrong, the Rochester carburetor is an excellent piece of equipment. On 75% of the trails, it works flawlessly. The only issues that arise come during extreme angles and bouncing around on rocky terrain. It can be really frustrating to climb a technical route and have the carburetor die half way through. I have two choices, convert to fuel injection or convert to propane. I opted for propane since there are no electrical components or computers. It is simple, proven technology that burns clean and is actually just a bolt-on solution.
I will admit that I did not know anything about propane except that it works great in my BBQ and my camper. Before I started, the first thing I did was research. I found out that propane is cheaper than gas, burns cleaner than gas, burns hotter than gas, never goes bad, gives the horsepower (approximately), no altitude issues, and just seems to run better. I also found out that converting to propane is quite a simple process. No modifications to the engine are required. Everything is a bolt on - in short - no modifications are needed to the engine to make it run. After researching the parts that would be needed and the cost, I decided to just do it.
I opted for dual tanks - just to be safe since propane is not something you can refill at your local gas station. It costs a bit more (an extra tank and mounting bracket) but having the extra fuel is comfort factor. It is not like your fuel gauge will let you know when you are running low. When the tank runs out, you are out. With a second tank, you just disconnect from one and rec-connect to the other (you can purchase auto-switch over valves but I did not see the need for the extra cost).
I purchased a complete kit. Not knowing a lot about what would be needed, I figured I would go with a company that has done this before. OK, so I had to pay a bit more than if I purchased all the parts myself but it was worth it - I got everything I would need in one purchase.
After getting the kit, I was surprised that there are really not a lot of components that you need and really not a lot of parts. After going over each piece, I can see where it would be really easy to overlook a few items so it was worth the price to get the complete kit. After looking at everything and the size of each piece, I laid out a plan where each would be placed. I started at the rear of the truck.
The Series has a perfect location for mounting the tanks in the rear. The standard 33.5 forklift tank fits on the "shelf" above each rear wheel. There are two brackets for each tank. Because of the weight, we built a steel plate that fits under the shelf to give it more strength. The plate is the width of the wheel well and 22" inches long. This plate is one item that needed to be fabricated. You can probably get by with something a bit smaller (this is 3/16" steel) but we happened to have a scrap piece at the shop. After careful measuring and drilling, the four straps (two for each tank) were securely bolted down.
We did a test fit with the tanks. FYI - there is no need to purchase new forklift tanks. Just visit any forklift rental or repair facility and you can purchase them used. I got aluminum tanks that are fairly new for $85/each. After adjusting the straps, they were locked in place. These are not going anywhere.
The next step is running the high pressure propane line to the engine compartment. One part you get in the kit is a coupling with a relief valve. This coupling has the relief valve on one end and the fitting for the propane line on the other. In the middle is a very sturdy bolt and nut for mounting this connection to something solid. You should mount this as close to the tanks as you can. The seat back in a Series has a middle support column that is a perfect location. Since I have two tanks, it is equal distant from each tank. One hole later, the coupler was mounted. I then cut enough propane line to reach the coupler and be able to switch between each tank with some propane line to spare. All you do is cut the line and then insert the fitting to the end of the line. Sounds easy but is a bit tricky since the fabric coating needs to be removed. Sounds easy again except the fabric coating is glued to the line. That is what sanding discs are for. Be careful since the propane line has steel strands in it. Once sanded, the new fittings were put on and a test fit was done.
Now that you have the tanks connected to the coupling, you now need to run the propane line from the coupling to the engine compartment. With my right hand drive Series, I decided to run the line along the frame rail on the drivers side all the way to the front. The Series makes this very easy to do. Just drill a hole above the frame rail behind the seat and pull the line to the front. I put in a rubber grommet in the new hole to protect the line and then used hose clamps and self tapping screws to secure the line to the top of the frame rail about every 12". Again, very easy to do since the seats and floor come out very easily. I just kept this process up until I reached the very front of the car. I did not cut the line yet since I wanted to make sure that I had the correct length AFTER mounting the components that the line needs to connect to.
Next in line are the filter, solenoid cut-off switch, and the regulator. This is where some thought came into play. The filter and solenoid are quite bulky and are designed to attach to the regulator directly (screw on fittings). The regulator needs to be mounted very securely but only has two screws/bolts. After some thought and debate, we decided to separate the regulator from the filter/solenoid. The filter (which is round like an ignition coil) was mounted to the front wall using a wall pipe clamp (actually it is an electrical conduit clamp). This bolted to the front very easily. Once mounted, the propane line was measured, cut, fitting installed, and then everything mounted in place. Both the propane line and filter/solenoid are secure. You will need to run an electrical wire to turn the solenoid on/off. This should be on the ignition switch OR on a separate switch. It is NOT required to have but is a valuable safety device. No power - no propane.
Next is mounting the regulator. We fabricated a simple metal plate which it bolts to. This plate was then welded to the frame and another metal support. Next, the two bolts were installed giving it a very secure and stable mounting platform. Now you need to connect the solenoid to the regulator (remember we opted NOT to connect these three pieces together). Pretty simple actually. Called up a hydraulic hose shop and had them make a custom propane line (make sure they know it is for propane and not oil as it is a different type of hose and fitting - this is very important). The cost of the line was less than $15 with the fittings. This new line was secured in place. With that complete, we have the tanks connected to the regulator with all the pieces in-between.
The regulator is in charge of lowering the pressure. If you have ever used propane, you may have noticed that it gets very cold. Freezing can be common so the regulator has 4 places for connections. One is for the high pressure propane line which is coming directly from the solenoid we just installed. There is another low pressure propane line that goes to the mixer which will be installed on the intake. The other two connections are for heater lines. Yes, the coolant keeps the regulator from freezing. In the kit there are two special "Y" connectors that you use to split the heater lines to the regulator. I opted to not use these. Instead, I just removed the heater entirely (damn thing didn't heat anyway). If you use the "Y" connectors, you need to make sure you have them connected correctly. On my truck, I ran the heater hose directly from the engine block to either side.
With the heater hoses connected, the next step is the mixer. This looks like a carburetor and sits on top of the intake manifold. For the Series, you can use the same throttle linkage and the bore on the intake is the same size so there are NO modifications necessary. Just bolt the mixer on and hook up the linkage. Once that is secure, you need to run the hose from the regulator to the mixer. Remember that the propane is very low pressure (about 5-7lbs). Put on the air filter (it bolts directly to the mixer) and you are complete.
Before starting, check all the propane fittings for leaks just like you would for any other gas line (soapy water). If you find any, tighten the fitting. I did NOT use any Teflon tape. Instead, use pipe dope. It hardens to give a more secure fit but stay flexible to prevent leaks (and allow you to remove it later if needed).
With everything ready, start up the engine. The Series fire right up. We did not have to make any adjustments except the idle screw. There are only two adjusters - one for the air/idle and one for the overall lean/rich of the propane. We left them at the factory settings and it roared to life. Once we were sure it would work (no doubt at any time), all the remaining gas lines, fuel pumps, gas tanks, etc were removed. Job complete.
In summary, there are a few differences. When you first start the car for the day, it will crank over 6-10 times before firing up. After that, it will fire up before the first crank every finishes. It starts extremely quickly. The next thing you will notice is how responsive the engine is. No hesitation at all. It also just seems to run better. No popping in the exhaust, no misfires, nothing. It purrs like a cat. We took it our for a quick run and were amazed as how low the rpms can get before you can stall it. I think we got it to about 200 before it even sounded like it would stall. We also found that it can crawl very well even with it idling. Going up a hill - it seemed to drive itself without stalling.
I finally got it out on the trails and was amazed how it drives now. There are hills that I had trouble with in 2/3rd gear which now I was climbing in 4th. It never seemed to bog down at all. Overall (so far) it was worth every penny.