Westfield Elevens

Question....
Which sparkplugs are best in a tuned A-series engine?
The spark plugs I use often malfunction after a year.
Perhaps a too hot or too cold spec plugs?

So what are you chaps using?

NGK BP 7 ES on a 1380cc, big valves and fast road cam but otherwise standard A Series. The advice I had was increase the BP[n] for a higher tuned engine so NGKBP5 for a standard 998cc and NGKBP9 for a race spec engine

Likewise I have NGK BP7ES fitted to my A-Series which is tuned to 100 bhp.

These plugs were fitted by the dyno testers and also recommended by the company who prepared my castings.

Thanks !

I use the bp7es too. The short lifespan of the plugs is probably caused by a faulty distributor (a knackered Lucas 23d4).
I replaced it with a programmable 123 ignition now..