Screened & unscreened ignition systems

Although originally written for problem solving in the Land Rover screened ignition system, there is a lot of information common to non-screened systems in other types of vehicles.

There are now sections listing a large number of Lucas coils & how they are coded & how they are expected to perform. Also a section on the effects of heat on coil breakdown, information that I discovered myself that can't be found on the internet.

For those who have waded through this before the main changes are on pages 2, 7, 9, 26, 37, 84, 85, 89, 90.

https://www.dropbox.com/s/ngxlc9rvolb124l/BRIGHT SPARKS FOR LAND ROVER v1.03.pdf?dl=0

fv1620 said:

Although originally written for problem solving in the Land Rover screened ignition system, there is a lot of information common to non-screened systems in other types of vehicles.

There are now sections listing a large number of Lucas coils & how they are coded & how they are expected to perform. Also a section on the effects of heat on coil breakdown, information that I discovered myself that can't be found on the internet.

For those who have waded through this before the main changes are on pages 2, 7, 9, 26, 37, 84, 85, 89, 90.

https://www.dropbox.com/s/ngxlc9rvolb124l/BRIGHT SPARKS FOR LAND ROVER v1.03.pdf?dl=0

Click to expand...

Thank you for this. It is brilliant! But, very complicated... I have a problem: I supply spare parts for Land Rovers in Malaysia. One of my customers is a workshop and they have this Series 2 ex-military which looks like it has a screened FFR system installed. Can we simply convert this to a conventional system?

If you want to simply do away with the screened ignition system and retain the 24v working. Then fit a normal distributor, leads & plugs. Ideally retain the 10v coil & filter box (contains ballast resistor but this is not the same value of resistance used in cars).
This has the advantage that the primary is loaded resistance & offsets some of the inductance thereby reducing the time constant of the circuit. This is of benefit particularly at high revs & under load, this is to offset the capacitive effect of the screened cables, which you no longer have so it is an advantage to retain this.
If you want to replace the 10v coil with a standard 12v coil it will work but a low temperatures there are theoretical disadvantages as discussed in the article. But cold morning starts may not be a problem in that part of the world.
If you want to convert to 12v then do all of the above & remove the filter unit as well as changing the bulbs, starter motor, wiper motors, relays & generator. About 35 years ago there was a company in Southampton that would convert your
Land Rover free of charge as they exported the 24v bits to foreign customers. Bear in mind early IIA FFR had a 40A charging system & later ones 90A. If you get problems with the 90A system there is another long article I have written on that subject.