Coil failure

[Mike Arnold]

I drove to Norfolk to collect some parts and see some old acquaintances. However, on my return up the A1 the rev counter dropped to zero and I lost power. I was recovered to home and confirmed my suspicion that the original Bosch coil had failed leaving the puniest of sparks.
So I went to my local parts shop and bought a new (standard) 3 ohm coil. A Lucas!
In a nod to the original I decided to mount it in a similar way to the Bosch. I will tell the story in pictures. Hover over the pictures to reveal the jpg name.
[tapping into coil.jpg] shows the way I had previously tapped off a supply for the electronic ignition by cutting into the cavity at the back of the coil. Obviously not now needed as I had to remove the armoured cable and old coil.
[coil 0.jpg] shows the ignition switch with the armour removed (note the sleeving and rubber boot where the coil supply cable comes out at the back of the switch). This is to protect the cable from the ragged edges of where I removed the armour using neanderthal techniques!
[coil 1.jpg] shows the rough blank I cut out to fit over the hole that the coil sits in.
[coil 2.jpg] shows the new coil fitted into the blank.
[coil 3.jpg] shows the painted unit.
[coil 4.jpg] shows the unit mounted back into the car.
The recovery truck driver talked about his old Range Rover and how it "eats" coils because they overheat. So, I have put a 1ohm ballast resistor in series with the coil to reduce the static dissipation from 65W to 37W to keep it a bit cooler. Obviously, dropping the current from 4.7A to 3.5A will reduce the spark but the electronic ignition will compensate. Anyway, the car runs as well as ever. Hopefully, for another 58 years.