Coil for Lumenition Optronic ignition

[Colin Symonds]

I need a new coil for my 4a fitted with the Lumenition Optronic ignition, Are the Lumenition coils MS4+ballast resistor, or MS6 worth the extra cost over the Lucas DLB110.  Ideas and any other recommendations please.    

[RobH]

Other 3 Ohm 12v coils to consider -  Bosch Blue coil,  Pertronix Flamethrower,  Remax ES3.     Lucas..... not so much.  

[Ian Vincent]

my go to coil is a Bosch Blue coil as used in VW Beetles etc.  They crop up on ebay occasionally.

On my car I actually have a Bosch red coil which I bought new and unused on ebay for a song.  The red coil is the one for use with a ballast resistor.  It seems to work fine with my Pertronix set up.

Rgds Ian

Edited August 11, 2022 by Ian Vincent

[Andy Moltu]

Use a 12v 3ohm coil (such as the Bosch Blue or Accuspark red) if you are running a 12v system. I think the Lumenition simply triggers the spark as an alternative to points & condensor rather than requiring a ballasted coil.

None of the early cars ran a ballast resistor, as far as I recal it was only the later TR6, some Spitfires and Stags. A ballast resistor set up has an 8 or 9v supply to the coil when running normally fed through a ballast resistor (or resistor wire) and uses a 1.5 ohm coil. On starting/cranking the resistor is bipassed to give 12v to aid starting)

If you run a coil intended for a ballasted system without a ballast resistor it is likely to overheat and or conk out prematurely. The ballast resistor generally isn't in the coil it is a separate entity in the wiring.

So unless you or a previous owner has modifed it to a ballasted system use a  12v coil.