Ok, thanks, Perry.  Yes, my plugs tend to start showing the effects of lead
fouling (from examining the plugs that is what it appears to be) after about
25 hours of 100LL.  This causes the SAG (Sparkplug Attention Getter) that I,
Tracy and now you have experienced.  Same conditions, high power setting
after takeoff (when you really want all the power you can get) and the
engine drops 150-200 rpm AGgg!  So far I 've just stuck in new plugs, but I
may try cleaning some of the plugs using local airport aircraft sparkplug
cleaner just to see if it helps.

Ed Anderson

I know Tracy is against this but he is a bit closed minded sometimes :-)
IMHO you guys ought to try multiple spark capacitor discharge ignition systems.
MSD for short. It is well proven to punch through spark plug deposits
for years. I built my first CD system back in the 60's using vacuum tubes
and mechanical vibrators for voltage conversion. Worked great
then as it will work great now.

You can use the tach pulse from the inductive pickup to fire
the CD multiple times. You can use Tracy ignition pulse for
the Chevy coils with an AND gate to fire the CD multiple times.
If you want to build your own I have several schematics.

Paul Lamar

Here are some more graphics on the advantages. Note the
required plug fire voltage goes up at lean air fuel ratios so a good CD
system will allow you to lean more and thereby further
improve the BSFC. This schematic is not very clear but
I can send you the original pdf file with parts list
and PC board layout on request.

Paul Lamar

Here is another idea. You can cut off the multiple spark
feature to save battery current and go into a limp home mode
if the alternator fails. Use only one spark.

This is a picture of Jim Mederer's 900 HP turbo 3 rotor
ignition systems. Those are six separate MSD ignition systems. 
One for each spark plug.

Jim won't start a rotary without MSD :-)

Paul Lamar
 
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