npanne Posted August 12, 2013 Share Posted August 12, 2013 Hopefully this is a schoolboy question - do bear with me...MkIV Spit - does it / doesn't it have a ballast resistor? How do I tell for sure? Are they visible? I've heard mention of an "incorporated" resistor wire???And how can I tell if I hve the right coil type? Before I pulled it all apart, it was running REALLY badly. At the time I gave up trying to diagnose it and ripped the old engine out, but now I'm getting it back together, I want to check I have the right coil for the wiring that's there - the electronic ignition has gone (which may have been the cause), but if I've got the wrong coil in there I'd rather find out now than spend a day trying to start an engine that's got no hope!Thanks all. Quote Link to comment Share on other sites More sharing options...
HMaze Posted August 12, 2013 Share Posted August 12, 2013 All MKIV1300 and 1500 had a Ballast resistor!The early MkIV had a solid one by the side of the coil, later ones had the resistor wire in the wiring harness.The coil was a 6 Volt one.Harry Quote Link to comment Share on other sites More sharing options...
npanne Posted August 12, 2013 Author Share Posted August 12, 2013 Thanks Harry,So given that I don't have a solid resistor anywhere on the bulkhead, I assume I've got a wire in there somewhere.Is there any way to test the coil I have to see whether it's 12v or 6v? I recall changing it once, but can't remember now whether this was before, after or coinciding with the running problems (it's been years since this car ran properly!).Thanks Quote Link to comment Share on other sites More sharing options...
npanne Posted August 12, 2013 Author Share Posted August 12, 2013 Have answered my own question - I've got the (correct) 6v one. Quote Link to comment Share on other sites More sharing options...
BarryH Posted August 13, 2013 Share Posted August 13, 2013 The major problem with the ballast resistor wire is that they break down with age and stop working and definitely should not be used with electronic ignition. Best thing to do is replace the ballast resitor wire with a 12 volt feed via the ignition switch and change the coil to match. Quote Link to comment Share on other sites More sharing options...
bodders1 Posted August 13, 2013 Share Posted August 13, 2013 bhuffer wrote: Best thing to do is replace the ballast resitor wire with a 12 volt feed via the ignition switch and change the coil to match....but only if you intend to fit electronic ignition, or your existing resistor wire has failed.If it is currently working as designed, why "fix" it when it doesn't need fixing? The whole idea behind ballast resistors and lower voltage coils was to give you a normal spark under normal running conditions, and a fatter spark with more "oomph" when cold starting. If you dispense with the ballast resistor and go over to a standard 12v system, you are losing this benefit. Quote Link to comment Share on other sites More sharing options...
npanne Posted August 13, 2013 Author Share Posted August 13, 2013 This might explain my previous problems, as I had electronic ignition fitted - presumably this was impacted by the presence of the resistor wire, and might account for why I could never get a decent spark from it. Quote Link to comment Share on other sites More sharing options...
rotoflex Posted August 14, 2013 Share Posted August 14, 2013 bodders1 wrote:...but only if you intend to fit electronic ignition, or your existing resistor wire has failed.The reason from earlier days was to fit a Lucas Sports Coil, which was only available as a 12v coil. It's cool to have, but I think now results just as good or better might had from solid-state ignition points and a 6-volt ignition system. Quote Link to comment Share on other sites More sharing options...
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