Lotus Elan

Omex 100 using distributor body & coil rather than coil pack

PostPost by: promotor » Fri May 24, 2024 2:12 pm

I've got an Omex 100 ECU that is for ignition only together with a wiring harness which uses only a couple of sensors - crank position sensor, throttle position sensor and ignition connection that is currently terminated with a 3 pin coil pack plug. I do not have a coil pack.
The ECU is powering up and working and I know the ECU was working properly when I bought it as I drove the car (not mine) that it was in.

So, the easy option would be to buy a coil pack and then I've got everything I need. However, it got me thinking about whether it's almost as easy to run a locked distributor ie one that has no advance capability so it's just a spark direction unit used in conjunction with a traditional coil : a coil pack is basically half a distributor (ie minus the points and condensor) plus a coil.

I have only just bought brand new spark plugs leads to suit the distributor on my twincam at fair expense so would like to use them if possible and not have to spend more money on a decent coil pack and plug leads to suit the coil pack.

Has anybody done something similar?
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PostPost by: promotor » Fri May 24, 2024 8:23 pm

I have managed to contact Omex and they have advised that a distributor can be used in this situation. For future reference, in case anyone follows a similar path, here is their interesting response :

"Simply join the two ECU coil wires together onto the single coil negative. You may need to adjust the option Coil Fact to get the correct coil charge time for your coil. A value of 12-16 is typical for a single coil. The correct value is the lowest value that makes maximum power, so can be found whilst dyno tuning. Almost any 12V coil can be used. Most people used to use a Lucas “sports” coil.

It can be better to leave the advance mechanisms working in the distributor as they keep the rotor arm aligned with the distributor cap better, though careful rotational placement of the distributor can allow it to work with a locked distributor."


Yellow and violet join together for the coil negative. Red is coil positive.

Looks like I will be pursuing this method providing all is well with the ECU.

(I really enjoyed typing with myself on this thread! :lol: :lol: )
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