As I understand it the spark reacts with the atmosphere to produce ozone which has the chemical formula O3 compared with oxygen O2
Ozone is so corrosive that when used commercially (water purification, washing contaminated laundry etc) it has to be produced at site and cannot be transported as there is no vessel material that is suitable.
I know that in laundry applications standard rubber components had to be changed for a different material due to premature failure.
It is the ozone that"corrodes" the belt so when Porsche became aware of this they put a clear plastic breather on the distributor to remove this gas as part of ongoing technical updates.
Now the speculation -
a) Maybe the modification was designed and tested over a relatively short period so with cars over 20 years old the rubber has deteriorated sufficiently to break.
b) Maybe deterioration of other components manifests itself as a larger spark and more ozone.
c) Maybe 20 year rubber is not that great generally.
I bi annually check that both rotor arms are turning and if I was to notice a slight drop in power I would even check these items at the side of the road.
Just disconnect the lead from each coil to distributor in turn and see if the car starts.
Ozone is so corrosive that when used commercially (water purification, washing contaminated laundry etc) it has to be produced at site and cannot be transported as there is no vessel material that is suitable.
I know that in laundry applications standard rubber components had to be changed for a different material due to premature failure.
It is the ozone that"corrodes" the belt so when Porsche became aware of this they put a clear plastic breather on the distributor to remove this gas as part of ongoing technical updates.
Now the speculation -
a) Maybe the modification was designed and tested over a relatively short period so with cars over 20 years old the rubber has deteriorated sufficiently to break.
b) Maybe deterioration of other components manifests itself as a larger spark and more ozone.
c) Maybe 20 year rubber is not that great generally.
I bi annually check that both rotor arms are turning and if I was to notice a slight drop in power I would even check these items at the side of the road.
Just disconnect the lead from each coil to distributor in turn and see if the car starts.