Upgrades · Ignition
Electronic Ignition for the Triumph Stag
Electronic ignition replaces the contact-breaker points with a trigger that does not wear. It will not make a healthy Stag faster, what it does is stop the timing quietly drifting away between services, which is why converted cars start better and stay in tune.
Photograph to follow, owner image to be added
What the points actually do, and why they drift
In the original system the distributor's cam opens and closes a pair of contact-breaker points. Each time they open, the current flowing through the coil's primary winding collapses and the secondary fires the spark. The mechanism is elegant and entirely mechanical, which is also its weakness. The rubbing heel that rides the cam wears, and as it wears the points gap closes; the contact faces pit and transfer material; and both effects change the moment the points open, which is the moment the spark fires. The result is timing that retards steadily over a few thousand miles, taking starting, smoothness and running temperature with it. The full explanation is in how a distributor works.
An electronic conversion replaces that mechanical switch with a non-contact trigger, typically optical or magnetic, driving a module that switches the coil. Nothing rubs, so nothing wears, and the trigger point stays exactly where it was set.
What it fixes, and what it does not
It fixes
- Timing drift between services as the points wear
- Points burning, pitting and the condenser as a failure item
- Inconsistent cold starting caused by a closed-up gap
- One recurring service task removed from the schedule
It does not fix
- A worn distributor shaft or bearing, the wobble remains
- A seized or lazy centrifugal or vacuum advance
- Poor earths, corroded connectors and tired HT leads
- Fuelling faults or a cooling system that has never been sorted
That second column matters. A conversion fitted to a distributor with a worn shaft simply triggers accurately from an inaccurate input, and the owner concludes that electronic ignition “did nothing”. Assess the distributor first; if it is tired, the money is better spent on a rebuild or a replacement unit than on a kit inside a worn one.
The two routes
1. A kit inside the original distributor
The trigger and its module fit on the existing baseplate in place of the points and condenser, and the original mechanical advance is retained. This is the cheapest route, keeps the car's original distributor in place, and is fully reversible, put the points back and you are standard again. Its limitation is that it inherits whatever condition the distributor is in, including its advance curves.
2. A complete replacement electronic distributor
A new unit with electronic triggering throughout, and in some designs a programmable or electronically controlled advance curve rather than weights and springs. It solves shaft wear and a worn advance mechanism at the same time, at higher cost. Keep the original distributor: it is a period part, it is worth money, and a future owner may want it.
Specific kits and distributors change over time, so rather than recommending a brand here, ask the Stag Owners Club and the marque specialists listed in resources which units owners are running successfully on the Triumph V8 now.
The coil and ballast question
This is where most conversions go wrong. Many cars run a ballast arrangement, so the coil operates on reduced voltage in normal running and receives full battery voltage while cranking. An electronic module may be designed to work with that arrangement and the standard coil, or it may specify a coil of a particular resistance with the ballast removed. Fitting a non-ballast coil to a ballasted car, or the reverse, gives a system that runs hot, misfires under load or fails early.
Establish what your car actually has before ordering anything, follow the kit manufacturer's wiring instructions for the specific part, and confirm the coil specification against those instructions rather than against a general rule. Background on the coil, ballast and HT side is in spark plugs, coil and firing order.
Fitting: the order that avoids trouble
- Assess the distributor. Check for shaft side-play and confirm the centrifugal and vacuum advance move freely and return. A tired unit should be rebuilt or replaced first.
- Record the existing timing. Note the current setting with a strobe before dismantling anything, so you have a reference to return to.
- Sort the earths and connections. Electronic modules are less tolerant of a poor earth than points are. Clean the distributor body earth path and the coil connections, see the electrics guide.
- Fit to the instructions. Observe polarity, route the module's wiring away from HT leads and exhaust heat, and secure it properly, vibration and heat kill modules.
- Re-time with a strobe. Non-negotiable. Set the timing dynamically at the specified engine speed, following ignition timing, and remember the Stag's quirk of timing from cylinder two.
- Keep the old parts. Bag the points, condenser and any removed components and keep them in the car's history file with the kit paperwork.
Value, originality and insurance
Buyers generally view a tidy, documented electronic ignition conversion positively, because it signals a car that is used and maintained rather than one that has been left to drift out of tune. Because the common kits are reversible and hidden under the distributor cap, they cost nothing in originality provided the original parts come with the car. Declare the change to your insurer along with every other modification, see the insurance guide. And keep the priority order straight: this is a worthwhile upgrade, but the cooling system and the timing chains come first.
Frequently asked questions
Is electronic ignition worth fitting to a Triumph Stag?
For a car that is driven rather than shown, yes. It removes contact-breaker points as a wearing, drifting item, so the timing you set stays where you set it and starting becomes more consistent. It does not add power to a healthy, correctly timed engine, and it cannot compensate for worn distributor bearings, tired advance mechanisms, poor earths or a fuelling fault.
Will electronic ignition make my Stag faster?
No, not on an engine that is already correctly timed and in good health. What it delivers is consistency: the spark timing stays accurate between services rather than drifting as the points face wears and the gap closes. Any perceived gain is usually the difference between a well-set engine and the drifted state the car had settled into.
Can an electronic ignition conversion be reversed?
The common kits that fit inside the original distributor in place of the points are reversible: keep the original points, condenser and paperwork, and the car can be returned to standard for a concours judge or a purist buyer. Fitting a complete replacement electronic distributor is also reversible provided you keep the original distributor, which you should, as it is a period-correct part and worth money.
Do I need to change the coil when fitting electronic ignition?
You need to match the coil to the system. Some electronic modules are designed to work with the standard coil and any ballast arrangement the car already has; others specify a particular coil resistance and no ballast. Mixing them is the most common cause of a conversion that runs hot, misfires at speed, or fails early, follow the manufacturer's instructions for that specific kit rather than the general advice on a forum.
Should I still check the ignition timing after fitting?
Yes, always, and with a strobe rather than statically. Fitting a trigger in place of the points can shift the effective timing point, so the timing must be reset afterwards. It is also the moment to check that the centrifugal and vacuum advance are still working, since the electronics do nothing about a seized advance mechanism.
Does electronic ignition help the Stag's overheating reputation?
Only indirectly. Ignition timing that has drifted retarded makes an engine run hotter, so holding the timing accurate removes one contributor. It is not a substitute for putting the cooling system right, which remains the single most important piece of work on any Stag.