I hate to keep beating this drum, but if you can walk into an Autozone and buy it, you shouldn't.

The heat range is too high. Street plugs have nose temps high enough to keep crap burned off at idle speed and 2,000 RPM light throttle. Once you are at WOT for more than a few minutes that street plug is too hot. You get cement boil around the center post. You manufacture a glow plug and loose control of ignition advance.

 

The NGK dash 10s are closer to ideal. the dash 11.5 is what racers use. Crosses to the dash 10s are also used in racing. Cheaper racers use Autolite AR2592. Special order from your friendly parts house. The last ones I bought were $7.00 for 4 plugs. Next day delivery. If you live near a circle track they may stock a few boxes. Air cooled dirt bikes use similar heat ranges.

 

Use inductive plug wires to kill off radio noise. Keep plug wires as short as is possible. Plug wires must touch nothing that is grounded.

 

Lynn E. Hanover

Incinerating rotary

engines since 1980.

David,

Thank you for the compliment.

I have installed a set of the -10 spark plugs and at this point they are long past the time where the stock plugs normally needed to be replaced. How long they will continue to work is unknown, but at least that one data point is consistent with the study and encouraging.