Matt306 Posted June 24, 2018 Share Posted June 24, 2018 I have brought one of these http://www.angclassiccarparts.co.uk/home/triumph-5981/spitfire/ignition/ignition-coil-lucas-spitfire-mkiv-1500 which appears to be the coil for ballasted Spits, my mark iv doesn't seem to have a ballast resistor, i might be looking in the wrong place for it though. Does it matter that mine doesnt have a ballast resistor? Whats are the benefits of the resistor? Quote Link to comment Share on other sites More sharing options...
glang Posted June 24, 2018 Share Posted June 24, 2018 Hi, I dont know if your specific model should have a ballasted coil but the resistor is normally mounted either on the coil or very close to it. Effectively these coils are designed to operate at a voltage quite a bit less than 12v and this lower voltage is achieved by dropping the excess across the resistor. During starting the high current draw of the starter motor causes the battery voltage to fall which in a normal set up can give a poor spark just in the worst moment. However by having a system that bypasses the resistor during cranking the correct voltage can be maintained which should give more reliable starting. Obviously the coils arent interchangeable.... Quote Link to comment Share on other sites More sharing options...
Clive Posted June 25, 2018 Share Posted June 25, 2018 The triumphs have the ballast resistor as part of the loom, from iffy memory a pink wire?? Check the wrong to your existing coil against a wiring diagram. As above, the resistor means the coil is supplied with 6v during running, but when starting gets the full 12v, actually less and possibly 9ish during cranking. That gives an extra juicy spark during cranking, ideal! So a good idea, but in reality the normal, unballasted system works well enough. Quote Link to comment Share on other sites More sharing options...
RobPearce Posted June 25, 2018 Share Posted June 25, 2018 Quoted from cliftyhanger- The triumphs have the ballast resistor as part of the loom, from iffy memory a pink wire?? Only on the later ones. Mk3 GT6 has a ceramic resistor mounted on the side of the coil. I'd expect a Mk4 Spitfire to have something similar. Quote Link to comment Share on other sites More sharing options...
Matt306 Posted June 25, 2018 Author Share Posted June 25, 2018 not seen anything there, i'll look again. Quote Link to comment Share on other sites More sharing options...
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