I remember that well as i had a flat spot on idle on the Mk2 at 1500rpm and i regularly replaced the O rings on the plates between the carbs and inlet manifold.
I have forgotten the name of the coils springs as they were special, the gap was 40 thou...
I had the Daytona Yellow Mexico, no stripes, in 1976 it was a `75 model just 6000 on the clock....no joke ...what a boring sounding motor...did go ok but i sold it 8 months later for another Lotus Cortina Mk1