Ford Vans 1961-1988 Repair Guides

Spark Plug Cables



Visually inspect the spark plug cables for burns, cuts, or breaks in the insulation. Check the spark plug boots and the nipples on the distributor cap and coil. Replace any damaged wiring. If no physical damage is obvious, the wires can be checked with an ohmmeter for excessive resistance. Resistance on these wires must not exceed 5000 ohms per foot.

To properly measure resistance, remove the wires from the plugs, and remove the distributor cap. Measure the resistance through the distributor cap at that end. Do not pierce any ignition wire for any reason. Measure only from the two ends.


When installing a new set of spark plug cables, replace the cables one at a time so there will be no mix-up. Start by replacing the longest cable first. Install the boot firmly over the spark plug. Route the wire exactly the same as the original. Insert the nipple firmly into the tower on the distributor cap. Repeat the process for each cable.

Silicone grease must be re-applied to the spark plug wires whenever they are removed. When removing the wires from the spark plugs, a special tool should be used. do not pull on the wires. Grasp and twist the boot to remove the wire. Whenever the high tension wires are removed from the plugs, coil, or distributor, silicone grease must be applied to the boot before reconnection. Use a clean small screwdriver blase to coat the entire interior surface with Ford silicone grease D7AZ-19A331-A, Dow Corning No. 111, or General Electric G-627, or their equivalents.