Letter Re Converting A Gasoline Engine Generator Set to Propane

Hi Jim,
A friend just sent this note to me and I thought I should pass it on to the SurvivalBlog readers:

I finished the generator conversion this weekend. I converted my generator from gasoline to propane. I had to order the big regulator (Garretson) from an online supplier.
These are a ‘demand’ [feed] regulator and will only deliver propane if something is pulling on it. Once the engine is shut off, it quits delivering gas. I started by removing the gas tank and fittings, then
stripped the carb down, removing everything that had anything to do with fuel delivery. I left the throttle and choke in place.
Using RTV/Silicone by Permatex, I plugged every hole and orifice in the carb except the main fuel delivery tube. Ace Hardware provided most of the brass fittings. The really tough fitting was the elbow that goes into the bottom of the carb. I managed to find an elbow with a heavy wall barb and just threaded the barb to match the threads in the carb. Everything else was ‘plug and play’.
Skagit Farm Supply was the source the tank regulator, 12 foot hose, and fittings to adapt the hose to the Garretson regulator. I elected to go with a tank regulator having about four times the flow capacity
of a barbeque grill regulator. I salvaged the propane tank fitting from an old barbecue grill and modified it by drilling out the passages and knocking out the check ball. This modification was done to assure
adequate gas flow in cold weather. I also took the needle valve apart and cleaned it, then applied a liberal dose of Crystolube 111 lubricant to the threads and “O” ring. Crystolube is an oxygen-safe
lubricant and is not affected by any petroleum product. I tightened the gland nut down to the point that the needle valve has enough drag/resistance so that it won’t move from vibration when the genset
is running.
The 1/4 inch fuel line (regulator to carb) was sourced from a Shuck’s Auto Supply store and the fuel line clamps were salvaged from the original gas tank. This really isn’t critical, as there is no positive pressure in this line.
I made the regulator bracket from a piece of 1/8″ x 3/4″ mild steel strap and installed it with fasteners I salvaged from the gas tank mounting.
Total cost of the conversion parts was in the neighborhood of $110 (perhaps a little less.)

So, how does it run? Perfectly. I should have removed the choke and will the next time I have the carb off. The choke is unnecessary, as the Garretson regulator has a ‘prime’ button it to give the carb a
shot of propane. The engine starts on the first pull and the mixture was very easy to adjust.

[My generator set is a] 4000/4400 Watt genset with Subaru Robin 9 h.p. engine. It should run about 12 hours on a ‘grill size’ tank of propane. I will eventually be plumbing this into the house propane system so I don’t have to mess with the little tanks.

I am impressed with the little Subaru Robin engine. It is an overhead cam / overhead valve engine and is beautifully made. It also runs at less than half the noise level of the last genset I had. I would say
this engine is equal to or better than a same-sized Honda engine, and having heard a Honda genset run, the Subaru is quieter. I would not hesitate to do this again.

Hope this can be beneficial to you and your readers. God Bless! – Steve, Still in Seattle