I have a '71 TR6 running a Pertronix Ignitor, Lucas Sport Coil, 7mm
silicone wires, new cap/rotor. Otherwise dead stock.
In a recent parade, the car never overheated, but appeared to be loading
up the plugs. Miss, hesitation, stall, and restart with black smoke. I
got caught in heavy construction traffic today with it and it did the
same thing. (It was about 90 degrees and sunny.)
So I stopped at the local autoparts place and asked for a set of plugs
one heat range hotter than the Bosch W8DC that are in it. They gave me
WR7DC, telling me that the resistor plugs did a better job of not
loading up due to a sharper "edge" on the spark.
I just pulled the old plugs and they look great. Nice and clean, no
signs of being fouled.
Now my questions:
1. Isn't a Bosch WR7DC one range _colder_ than a W8AC? (I know Bosch
and NGK have opposite numbering schemes but I can never recall which is
which.)
2. Anyone successfully using the WR7DC on a stock engine?
3. What else should I be looking at that would cause the "plug loading"
symptoms I described?
Thanks!
Bill Elliott
Lake Barrington, IL
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