Triumph Repair: Ignition coil voltage..., electronic ignition system, starter solenoid

Question
QUESTION: Howard,
I have a 1979 Spitfire, the ignition coil was bad (leaking) so I replaced with a 12 v coil. I understand they actually use a 6 v coil. Is this correct?

ANSWER: Hi Steve,

Yes, they came with a 6v coil which used a ballasted resister and a bypass power system from the starter solenoid. If you have the Opus/Lucas system with a large box on the side of the distributor with three wires and the vacuum unit mounted directly on that box, then you have the original system (unlikely).

However, this ignition system failed so often that most owners replaced the ignition system with either a aftermarket electronic ignition or even a pointed distributor system.

So you need to ID what ignition system you have to decide which coil to use. Several aftermarket systems just replaced the original pick-up inside and clipped the three wires off of the box and bolted their unit inside where the pick-up was. Most of these systems used a 6v coil.

Look at the three wires coming out of the box to see if they are cut off and look inside the distributor to see what name is on the pick-up unit.

The only way you should use a 12v coil is if you don't use the resister wire that came with the original system nor any external resister.

Howard

---------- FOLLOW-UP ----------

QUESTION: Thanks for the replay. I'm sure I have the original electronic ignition system as described by you. So you say this system is unreliable? This car has not run in 12 years so that is a potential problem area I will have to keep an eye on.

Answer
True, I worked for MG, Triumph & Jag dealerships for many years and there were very few that had the "Box on the side" on the distributor (Opus/Lucas)that didn't get replaced once or more times while they were in warranty. Soon, several companies started making optional replacements. Some of them were just as unreliable as the original. Some owners went so far as to locate an earlier model that had a pointed ignition system and used that. Some were not as expensive as the Opus/Lucas so they didn't mind purchasing an extra one to carry as a spare. Working at the dealership I only handled the warranty on the original so I don't know how long the others survived. Even some name brand companies made replacements.

One of my personal TR-7s had the "Box" fail so I went to an extreme and changed the upper shaft to accept a points cam and I drilled and taped the mounting plate and installed points. I even used that distributor on a experimental Alcohol engine in a DOE grant project I received. That was a lot of work so I don't recommend that rout.

However, some earlier Spitfires had pointed ignition systems so if your "Box" tests as bad you might look at the price of some of the aftermarket replacements and an older pointed distributor.

When I would get a car that had been stored for any length of time I had a procedure I had to follow when it wouldn't run and that is, Test Compression first, Ignition second and Fuel last.
But when I seen it had the "Box" I tested ignition first.

Howard