In the 1930's some Volvo trucks (models unknown except some "roundnose" 1939-40) were fitted with Volvo-built Hesselman engines; these were fuel oil (diesel) burning but completely magneto-sparkplug ignition engines, created by Jonas Hesselman in the mid-late 1920's.
One source said some Volvo T-40 Series tractors (T-43??) were fitted with this type engine up into 1950 or so.
The magneto was special high-tension, and special sparkplugs were used; I'm trying to determine what sparkplugs were originally used and their size (18mm or 7/8-18??) as well as modern equivalents.
Export Case tractors (to AU) and some US Waukesha-Hesselmans used Bosch DM-20-S-148 and DM-20-S-149 plugs
Does anyone here have any Volvo-Hesselman literature that spercifies the plug to be used, or a good sparkplug catalog published in the late 30's to the late 40's that covers Volvo trucks/tractors, and/or Scania trucks, which also used such engines 1932-36 and possibly later??
I have some info on US plugs, and the Wauk-Hesselman Gen'l Instr's listing plugs.
Any comments appreciated. Feel free to reply to Bud pitybud@msn.com.