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MG MGB Technical - Ballast Resistor


How do i go about bypassing the ballast resistor on my 1978 MGB GT? how do i identify the ballast resistor ie, what colour wire?

I'm in the process of doing a v8 conversion with electronic ignition so i need a 12 volt feed to the coil.

Any info would be great,

Gavin Jewkes

This is what I previously wrote:

If any of you with a late rubber bumper MGB is looking for the ballast resistor for the ignition coil, I know where it is! These cars have the resistor built into the front headlamp wiring harness. It
CD Dewey

It should be a *white* wire on the front of the fusebox, usually sharing the same spade connector as the white from the ignition switch (76 and earlier) or white/brown from the ignition relay (77 and later).

The only wires involving red on the fusebox should be the single red/green to the the front of either of the top two fuses which comes from the parking position of the main lighting switch, and four red wires on the back of the top two fuses which go to the parking lights at each corner.

Depending on what electronic ignition system you fit you may have to change the coil if you are going to bypass the ballast resistance to it, otherwise you will overheat it and possibly overstress the electronics switching it. Often whilst you provide a new 12v unballasted supply to the *electronics*, you leave the ballasted conenction to the coil in place. It actually improves cold starting, and is detremental to remove it.
Paul Hunt 2

This thread was discussed between 03/05/2006 and 05/05/2006

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