LCGB Forums

Could someone please tell me the correct spark plug to use on my 150D?
The plug that was in the engine when I bought the 150D (and it appeared to be running properly) was an NGK B6H S.
Vittorio Tessera quotes a Bosch 225 short thread in his Restoration Book, but I have also seen other plug numbers mentioned in this forum.
Is the B6H S correct for mine?

Just to confuse the issue further, there is also an NGK BR6H S plug.
Googling the difference, it appears the extra R stands for Resistor, to cut radio interference.

The original recommendation was for a short reach Bosch 240. Fuel and oils have changed dramatically since the 50s so now the current recommendation is for the short reach Bosch 225. Basically an NGK B6HS. B=shell with 13/16" across flats, 6=heat range (low numbers are hotter), H=short reach, S=standard firing end. More details here:

https://www.ngk.com/ngk-spark-plug-numbering-systems

You do not want a resistor plug as the ignition system is not powerful enough.

Many thanks John.
I will stick with the original then.