Just looked up the Denso Iridium spark plugs that I think will do a 4 cyl TR - Denso IWF20 - Just £8.00 a pop. I am in the old world of spark plugs costing one to two pounds a set or each as it is today - Do you have road test experience of these items in a TR Peter? Should we now be ditching our NGK BP6HS (TR2-4A) and NGK BP6ES (TR5-6 PI) ?
No experience yet, they're sitting on the shelf. My aim is to run really lean at cruise and not to suffer weak sparks under boost: wire plugs should do both. I am always wary of sales blurb but wire plugs are based on sound data, in textbooks and publications. eg thsi on ignting lean mixtures:
So they should help starting. The carb may be richended but only a small fraction of petrol will vapourise in a cold engine, so the mixture at the plug will be lean.