Ownership / Electrical

Electrical

The Stag is a 1970s Lucas car, negative earth, with more electrical equipment than most of its contemporaries — and most of its "electrical gremlins" come down to tired earths and connectors rather than anything exotic.

The basics

The system is conventional for its date: negative earth, Lucas alternator charging, and the usual Lucas fusebox and connectors behind it. None of that is inherently fragile — but age is. Half a century of damp, vibration and heat brings corroded earths and corroded connections, and those cause a remarkably wide range of intermittent faults: gauges that read low or not at all, lights that dim when something else is switched on, a fan that runs slowly or not when it should. Chase the earths and connections before condemning components; a great many "failed" Stag components turn out to have been starved of a decent return path. Clean, tight, bright earths are the single best thing you can do for a Stag's electrical health, and they cost almost nothing.

The cooling fans

The Stag relies on electric cooling fans, and a lazy fan — or its tired wiring and relay — is a genuine contributor to the overheating the car is famous for. Check that the fans cut in when they should, and that they cut in with conviction rather than turning over apologetically. Where the wiring is original and the voltage at the motor is down, a relay upgrade and a good dedicated earth let the fans pull full current and do the work they were fitted to do. It is one of the places where an electrical fault and a cooling fault are really the same fault, which is why an overheating Stag is worth testing with a meter before it is worth buying parts for. See the cooling upgrades guide for the cooling side of the same problem.

Sensible upgrades

A small number of electrical changes earn their keep. Electronic ignition in place of the points gives reliable starting and steady timing; relay-fed headlamps give brighter lights and put less load through the switch; and relay upgrades for the cooling fans, as above, address a real weakness. All three are popular, all three are worthwhile, and — importantly — all three are reversible, which keeps them in keeping with sympathetic ownership of an original car.

Keeping it reliable

The order of work is always the same: clean, tight earths and connectors first; then a sound charging system; and then never ignore a flickering warning light or a gauge that has stopped reading, because on a Stag both are usually telling you something true. Confirm wiring against the diagram for your car — the looms and equipment vary between Mk1 and Mk2 and between markets.