TRACTOR VAPORISING OIL - POWER PARAFFIN
The post war Ferguson TEA 20 tractor was designed around a petrol engine.
As a subsitute for petrol, TVO was developed. Paraffin (kerosene) was commonly used as a domestic heating fuel and was un-taxed. Paraffin has an octane rating of zero and would damage an engine built for petrol. The manufacture of paraffin involves the removal of aromatic hydrocarbons from what is now sold as heating oil . These aromatics have an octane rating, so adding some of that otherwise waste product material back in a controlled manner into paraffin gave TVO. The resulting octane rating of TVO was somewhere between 55 and 70.
In practice TVO had most of the properties of paraffin including the need for heating to encourage vapourisation. As a result the exhaust and inlet manifolds were adapted so that more heat from the first warmed the latter. To get the tractor to start from cold a second small fuel tank was added that contained petrol. The tractor was started on the (expensive) petrol then once the engine was warm, the fuel supply switched over to TVO. So long as the engine was working hard (eg on the land, ploughing, pulling a load) the TVO would burn well. Under light conditions (travelling unloaded on the highway), the engine was better on petrol.
The phrase petrol-paraffin is often used to describe engines that use TVO. This can be interpreted either as : the use of the two fuels, starting on petrol then switching to the paraffin-based TVO: the use of a mixture of petrol and paraffin as a substitute for the proper TVO
TVO is no longer available in South Africa.
RECIPE FOR MAKING YOUR OWN TVO
Petrol (unleaded is absolutely fine for a Ferguson tractor) 98 Octane
28 Second Heating Oil 20 Octane
Aim for an Octane value between 55 and 70
55 if doing very hard work
70 if doing topping and the like
To give you some idea of the sums:-
1 petrol and 1 heating oil (Power paraffin) comes out at 59 Octane
2 petrol and 1 heating oil comes out at 72 Octane
1 petrol and 2 heating oil comes out at 46 Octane
Petrol on its own is suitable for road runs (with the heat shield removed).
Octane is not the only factor, but is provides a good guide line
Diesel fuel is designed to cause ignition by compression and will encourage pinking. It is not designed to burn in TVO tractors, and no upper cylinder lubricant is required in these tractors, so do not use anything other than petrol and heating oil.
Using fuel which does not burn completely will destroy the lubricating properties of the oil and that (in a Ferguson TE tractor) will result in wear to the cam shaft bushes and then loss of oil pressure from cam shaft bushes. Loss of oil pressure will, then result in damage to the crank shaft. Lubricating oil in a TVO tractor's engine should be changed according to the Tractor Instruction book.
IMPORTANT: NEVER USE ILLUMINATING PARAFFIN !
Heat shield must be fitted for use with TVO & removed when using petrol only
THIS ARTICLE IS FOR INFOMATIVE PURPOSES ONLY - PLEASE DO NOT PHONE WITH QUESTIONS