Letter Re: Running Chainsaws on Ethanol & Home Alcohol Production Stills

About your comments [on Thursday] and others in regard to kerosene use in a gasoline engine: From anything I’ve experienced, you are correct about it not being as simple as some have posted. Engines that were built for “all fuel” use – including distillate and kerosene, had very low compression ratios – usually around 5 to 1. Low compression makes a low-power, inefficient engine. The carburetors were jetted differently, a twin fuel tank setup used, a selector-valve installed for quick fuel changeover, and a closeable air-shutter on the radiator to keep the engine hot. You started the engine on gasoline, got it good and hot, then slowly switched over to kerosene. When it came time to shut the engine off, you had to switch back to gasoline first -otherwise once cool, it would not start again.

Modern automotive gasoline engines with computer controls can be anywhere from 9-to-1 to a 11-to-1 compression-ratio. Older automotive engines, if not made to run on “high test” tended to be in the 8 or 9 to 1 range. Modern heavy-duty industrial use gasoline engines – and other off-road equipment – including lawn-mowers and such, tend to run a compression ratio of 8.5 to 1 which is too high for kerosene use.

I was a John Deere tractor mechanic in the 1960s/70s and used to work on a lot of “all fuel tractors.” Deere and other companies made them up to the late 1950s. We usually converted them to higher compression ratios to run on straight gasoline. This way, they made more power and ran more efficiently. In fact, we sometimes took standard gasoline tractors – and installed “high altitude” pistons to make them even more powerful. There are still a few all-fuelers around being used – including the two I own. My 1937 Deere [Model] BO still has the original all-fuel parts including the radiator shutters. I have to get it really hot before I dare switch it over to kerosene. And, after working it – if I park it with the engine idling and still hooked on kerosene – it will cool down, start backfiring and eventually die – unless I either get it hot again – or switch over to gasoline.

Just to show the power difference, a 1956 John Deere 720 all-fuel tractor with a 360 cubic inch engine put out a max. horsepower of 42 horsepower. Same engine and tractor in the gasoline-only version put out a max. of 55 horsepower and ran 20% more efficiently. Same tractor in diesel version put out a max. horsepower of 56 and ran twice as efficiently as the all-fuel version. Seems using diesel power is a no-brainer. If you have some kerosene in reserve, stick it in a diesel. – John from Central New York