At every tune-up/inspection, visually check the spark plug cables for burns cuts, or breaks in the insulation. Check the boots and the nipples on the distributor cap and/or coil. Replace any damaged wiring.
Every 50,000 miles (80,000 Km) or 60 months, the resistance of the wires should be checked with an ohmmeter. Wires with excessive resistance will cause misfiring, and may make the engine difficult to start in damp weather.
Minimum spark plug wire resistance should be 250 ohms per inch (635 ohms per centimeter) and maximum resistance should be 1,000 ohms per inch (2,540 ohms per centimeter).