Mark,

There may well be a duty cycle problem, but I doubt it. Older ignitions used a single coil of similar type firing all 8 cylinders. I would be more likely to suggest it was a "bathtub failure curve" failure of the solid state "trigger" circuit.

Bill Jepson

 

Ah-h-h; and why would duty cycle not have an effect on temperature and failure rate of the ‘trigger’ circuit?  The solid state components do dissipate some heat, and the more cycles, the more heat and other effects leading to failure.

 

Al G