Categories: Green

Simple DIY Gasoline to LP Conversion

Use at your own risk LP can be dangerous. This conversion works with 4 stroke engines that are designed to be operated at a set rpm like a lawnmower, log splitter or a pump. It would not work on a 2 stroke engine or something like a car where the rpm’s are constantly changing. It’s a little harder to start an engine on LP, but it can be done. Electric start or a touch of starting fluid makes it easier. Be careful not to over rev the motor. The conversion by-passes the carberator and the speed governor. It can breath new life into an engine with a gummed up or broken carberator. Be sure to click on the picture to view all of the photos.

I read about converting gas engines to run on LP. I decided to get my hands dirty a couple years ago when my lawnmower would not start. I built my first conversion from an old plumbers propane torch. I removed the torch tip and added about two feet of copper tube to the torch. I brazed it together, but a rubber hose and a clamp will work too. I secured the 1 lb bottle to the push bar on the mower and feed the end of the tube into the air intake. I opened the valve on the torch and tried to start the mower. After a few pulls it sputtered and stalled. I opened the valve a little more and it started right up. It worked, but it would freeze the bottle if I ran the motor too fast and too long.

I solved the freezing problem by upgrading to a gas grill regulator. Some regulators are fixed and some are adjustable. Most adjustable regulators have a plastic or metal cover about the size of a quarter in the center of the regulator. Pop out the cover and you will find a threaded plug with slot for a screw driver. If you turn the plug in it pushes against a spring and feeds more fuel. Turning it out decreases the fuel. You will probably need to screw the plug in several turns to reach the rpms you need. My regulator had a rubber hose that connected to the gas valves on the grill. I cut the hose at the valves, mounted the tank to the mower and fed the rubber hose into the air intake. It worked like a charm.

I used the same technique to convert a small snapper riding mower. It worked well because the mower was set up to run at a fixed rpm. It had a 5 forward speeds and separate controls for the mower blades. I use the same tank, regulator and hose to run my log splitter. LP is cheaper and burns cleaner than gasoline. It should allow your engine to last longer, reduce emissions and decrease the use of oil.