Some interesting stuff that your rarely hear about plugs, and other stuff.

(1) compare a MC-59 and the MC-8 or MC-9. Look at the difference in the size of the "hole" where the plug element resides. The MC-59 hole is enormous,, the K&B1L is the same heat range as the 59 but will not change your button volume.

(2) compare a O.S.8 to any of the above and look at the length difference of the threaded portion, the O.S.8 is shorter.

The "flash point" of methanol is nearly twice as low as nitromethane, Methanol is 61*F and Nitromethane is 110*F.

Higher combustion chamber volume has a "cooling effect", where lower volume goes in the heating direction of the same engine.

Different plug heat ranges are like your ignition timing in these glowplug engines.

Combustion chamber volumes can affect timing also considering air temp and moisture content