I replaced the standard contact breaker ignition in the car with an Aldon Ignitor Electronic Ignition. This is the same unit that is sold in the USA under the Pertronix name. These systems come in both positive earth and negative earth. It is important to install the correct version as they are not interchangeable.
The standard unit for a negative earth MGA with the DM2 distributor is the 4-ULU142A.
The standard unit for a positive earth MGA with the DM2 distributor is the LU149P12.
Fitment is straight forward and, except for the 2 power cables, is all contained within the distributor, as shown below:
|The contact breakers are removed in their entirety from the base plate and the electronic trigger mechanism is attached using the existing studs and tapped holes. The two cables are secured with a cable tie and pass through a grommet in the distributor wall.|
|The magnetic rotor fits over the contact breaker cam. It will only fit in four positions, any of which is okay.|
|Finally the rotor arm is replaced.|
|Externally, the 2 power leads are connected to the coil. For a
negative earth car the red lead goes to the +ve terminal and the black
cable to the -ve terminal. The distributor is then timed in exactly the
same way as a conventional ignition.
I found much improved performance with this system over the conventional breaker ignition. I also fitted a 'Sports Coil' which made a further very noticeable improvement.