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Very informative article, David!
It reminds me though of an issue I encountered some years ago with a point-triggered CD conversion on my 495 c.i. big block Chev (single 850 Holley, factory 12.5:1 CR and ZL1 cam (~ 265° @ 0.050") I discovered that with the CD system switched on, the engine would not run smoothly at cruise unless the vacuum advance (~15° @ 12"Hg.) was disconnected.
The best explanation I could come up with was that at the high cruise vacuum (didn't have a vac. gage) of a stout-engined '70 Camaro with 4.10:1 gears (3,000 RPM at 55 MPH), the total advance of perhaps 45° meant that at the ignition point the cylinder pressure was so low that literally there weren't enough oxygen and hydrocarbons molecules present in or near the arc to initiate combustion.
This preamble is a long wind-up to the question: Does the relatively short spark duration of a CD ignition like this Crane unit imply any similar risk of misfire if one twists the knobs too enthusiastically?
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