What spark plugs are best with a pulley mod?
The stock plugs on the first run cars, the AGSF12FM1 Motorcraft plugs, are pretty close to the coldest plugs I have been able to find (one heat range colder than stock). These are the plugs I would tend to recommend for a car with a smaller pulley but no chip, and are the plugs I have used for several thousand miles on my personal Cobra. NGK TR6 plugs are hotter than the 12FM1s, however, these plugs as well as the Denso Iridium plugs seem to work well for chipped cars with a pulley.
