First is that the engine runs better on trailing plugs only than it does
 > > > on leading only.  Timing is right on according to Tracy's recommended
 > > > setting of 20 BTDC at 5000 and <24".  Using the unshrouded NGK B9EGV
 > > > plugs at .025 gap.

At low speeds there should be little stress on the secondary ignition system.
The charge is being carried past the leading plug at high speed and it
becomes a problem at high RPM. I gap the plugs at .010" and drive it with an
MSD-6T. At low speed there should be no trouble lighting anything. It sounds
more like that particular RPM is an over lean spot. That is the only time I
can think of where the trailing would work better than the leading. At high
speed loosing the leading will cost a bunch of power. But, loosing the
trailing will just change the sound a little bit. Lighting both at the same
time makes very little difference power wise, but retarding the trailing gets
a smoother idle, and a lower HC pollution number. The timing at 20 BTDC is
plenty with low octane gas. Check often that all of the air is out of the
block. An exciting time isn't it?

Lynn E. Hanover

 
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