Later cars usually have carbon-cored leads, which are more flexible, though the core can break easily if roughly treated. Such leads have a built-in
and generally do not need extra suppressors.
leads are sold as complete sets, with the distributor and coil connections and plug caps already crimped on.
Simply remove the old leads, one at a time to avoid confusion, and replace with the new ones.
Note that when fitting or removing plug leads you should always push or pull the cap, not the lead, to avoid straining the lead and possibly pulling it away from its terminal connector.
Leads sometimes run through guides which hold them apart or away from hot,areas. Always refit them in their guides.
Types of lead and connectors
You can tell copper-cored cable by its stiffness, especially when cold, and by the type of connectors fitted to it. Carbon-cored cable is quite flexible - but do not kink it, as the core snaps easily. Carbon cable has resistance marked on the insulating sheath.
Carbon-cored cable has terminals already crimped on. These are a push-in fit to the distributor and coil, and are covered by rubber dust
. Ease back the seals along the lead and fit the connectors into the coil and
. Fix the dust seals.
Copper-cored cable uses screw-on connectors which you fit yourself after cutting the cable to the correct length. There may be a screw collar over a terminal which you crimp on with pliers, or a terminal washer over which the strands are splayed. A screw collar then clamps the washer on to its connection. A third type has a screw which pierces the strands of the core.
Fitting a connector to copper-cored cable
When fitting a screw-on connector to copper-cored cable using a crimp-on terminal or a washer, remove about z in. (13 mm) of
from the end of the lead with a sharp knife. Take care not to cut into the wire core. Thread on the collar. Fit a crimp-on terminal by folding up the wings and flattening them with pliers. Fit a terminal washer by threading the core through the washer and bending the strands back around it.
For a screw terminal, do not remove any insulation. Insert the lead into the connector, making sure that the screw is in line with the cable core. Tighten the screw to pierce the core.
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If your car's instrument panel includes an
, it will tell you how well the charging system is working - the difference between the
going into the
and the power being used from it.