| Extra stress (=heat) on the coil, extra wear of the cap and rotor and, to | a lesser degree, of the ignition cables.
Nonsense ; a bigger gap just requires a higher voltage ( & more amps too, I believe ) to produce a spark, you can see in books under " dielectric breakdown". Users can use bigger gaps without any damage, only torque will drop & noise rises fast with rpm when voltage / ampere is inadequate.
My plugs ( fed by high efficiency *cables, 2 ohm/ft, in a honda F20A )' gaps are 3mm, to get a 3mm long spark to burn petrol vapour fstr = more torque. This must not be done on any 4 cylinder engine with just a small built-in coil & plain carbon-core cables ; a 1mm gap needs just 4.46kv, but a 3mm gap needs 12kv ( my estimate ) to produce a spark.
- can feed enough voltage & ampere to my 3mm gaps without any fast drop in torque, or noise rise, up to 3350 rpm ( no chance / need to spin fstr ; legal speed limit = 110kph ).
My mitsubishi 4G15P engine has a set of Sparko 3 core cables ( 240 ohm /ft, medium efficiency ), my plug gaps here are 2mm.