COP Ignition Development

Resistor plugs go with modern electronic ignitions. The internal resistance is about 5.6K Ohms. I plan on using them with short spiral core plug plug wires. The resistance not only helps reduce EMI, it also reduces the current, prolonging spark duration. The spark discharge is less singular, and appears as finer multiple discharges between electrodes.

I think the old used plugs were contaminated. Even though they were properly gapped, the spark quality varied by plug. The sparks were taking weird paths. I have four new resistor plugs bought by mistake, and used those to replace the problem plugs. The communications problem went away, so I went out and purchased new plugs. The sparks look good, and are uniform for all plugs.