Hey Scott,

I just checked my filler gauge and 12 thou is .30 mm which is what I set mine at.
The normal plugs are ok with it but Iridium no good.

What I did notice is that the iridium rod is much softer material and tends to bend when setting the gap so this could explain the misfiring.

I will investigate further and report back .

I think the other blokes are using bigger gaps for the iridium.

regards