Zeke I had a similar problem when I switched to an MSD ignition. I had one
of those hot Lucas competition coils The car ran fine until about 4K and
then it just would misbehave and it was a real task to get it to 6K in the
lower gears and it just went nowhere in top. I tried everything. Finally I
took it to my tuning Guru. He put it on an Allen Smartscope and spotted the
problem within 2 minutes.
My spark voltage was about 80,000, but as rpm increased the duration was
dropping and above 4k, it was so fast that it wasn't firing long enough to
propagate a good flame. He got me an epoxy filled Niehoff coil (can't recall
the #) the produced a much lower voltage than the Lucas. Now my final
voltage was a lot lower, but I had a spark that lasted enough to get things
burning. After that, the little bugger was pulling hard at 7500.
I think that coil sold for less than $20. A nice cheap fix.
Another case of where more isn't always better.
GJB
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