Robin2:
Are you sure you're not mixing that up with paraffin (kerosene) - which used to be referred to (when I was small) as TVO or Tractor Vaporizing Oil. AFAIK those engines continued to need a spark when running on paraffin. I have never come across the phrase "diesel engine" to mean anything other than a compression ignition engine. It is probably possible to run a spark ignition engine with diesel fuel but it would not be a compression ignition engine. And AFAIK it is not possible to run a CI engine on petrol as it will not ignite spontaneously the way that the heavier diesel fuel does.Rudolf Diesel's original engine used high pressure air blast injection.
...R
Quite right, Robin.
I was thinking of our old John Deer tractor. It always used spark to fire the Diesel fuel. One hell-of-a-spark from a magneto. If the engine was hot it would start directly burning Diesel oil, but not if cold.
On the other hand, my father-in-law had several International Harvester tractors the started on gasoline and had compression release to stop the autoignition. Then when warmed a bit, you moved a big lever that stopped the ignition and the compression release and ran full auto ignition Diesel.
Then there was the Oliver tractors that were full Diesel, but were started by ether from a spray can. The air/ether mixture would auto-ignite at a log temperature and spin the engine fast enough to start, sometimes!
I wonder how the OP intends to supply the engine bearings with lubrication?
Paul