I have sort of a frankenstein RX7 with a lot of different parts. The basics are a NA Rotary Engineering "Turbo Alternative" 13b. The ignition is one I made from Jeff20B's diagrams of the waste spark system. I have three j-109 igniters firing three Blaster coils. The igniters are mounted on an aluminum heat sink in the air flow in front of the radiator.
A few days ago the car was running very badly with intermittent spark. I pulled the plugs and the front rotor was black with carbon, the rear was tan for the plugs. I put new plugs in and changed the leading coil igniter - all seemed well. This morning, almost to work, the one rotor went out (I assume it is the front igniter again). What could be the problem?

 

No heat sink grease? Bad coil that flakes out when it warms up?

 

Thanks Jeff - I did use the heat sink grease but I will take a closer look at the coil. For now it is back on the road with a new igniter.