My SM doesn't get used a lot (I prefer fanging about in a 18 YO Peugeot 306 S16, one of David Cavanagh's "too good to wreck" cars). I started it a couple of days ago no problems but when I went to start it today it just refused to co-operate.
Checked, yes there was fuel at the carbs. Yes there was a spark from a plug lead to the cam cover, both banks. OK, has to be plugs.
This was odd as I had fitted new NGK Iridium BPR5ETX plugs not all that long ago. These are supposed to be a superior plug to conventional plugs and you can read about how good they are at NGK Spark Plugs Australia
Swapped them for a set of normal NGK BP5ES plugs and it started instantly.
I'm not sure what conclusions to draw from this. The Iridium plugs did have black sooty deposits and maybe they are not hot enough for the way I use the SM.