mikeyb Posted November 2, 2016 Share Posted November 2, 2016 As the garage/shed sort out progresses, I have a box that is accumulating literally dozens of ignition coils. Short of putting each one on a car is turn, is there a foolproof test method - for example using test meter? Quote Link to comment Share on other sites More sharing options...
Velocita Rosso Posted November 2, 2016 Share Posted November 2, 2016 Meter across terminals and look for ohm rating? Quote Link to comment Share on other sites More sharing options...
sparky_spit Posted November 2, 2016 Share Posted November 2, 2016 Certainly test the resistance across the primary and secondary winding of each unit. If nothing else, it will tell you which ones are for ballasted systems and which are not.The casings are not an earth source for the coil, although they are obviously earthed via their mounting bolts, so it would be wise to check for any low resistance between the windings and the case, indicating an insulation breakdown.TBH, unless the coil is really knackered, all this isn't going to tell you much as most coils get changed out as faulty when they fail in service under load and when hot. I suppose you could heat them in the oven (make sure Ivi isn't around!!) and check the resistance readings as above.Even then, you'd want to run each of them on a car for a few weeks to be 100% sure they're okay.When I had coil trouble in the Spitfire some years ago I cable-tied another coil on top of the other so I could easily swap the 3 leads over as necessary. **Edit** Sorry, meant to add that the primary winding (from +ve terminal to the -ve terminal) will be 3.2 ohms for non-ballasted, 1.6 ohms for ballasted, and the secondary winding (from the +ve terminal to the centre HT terminal) will be about 6K ohms. There should be no reading between any terminal and the casing. Quote Link to comment Share on other sites More sharing options...
thescrapman Posted November 2, 2016 Share Posted November 2, 2016 I gave up amd weighed my 30-odd coils in. Quote Link to comment Share on other sites More sharing options...
RedRooster Posted November 2, 2016 Share Posted November 2, 2016 Mikey have you a megger? a DVM is no good for the insulation test. Quote Link to comment Share on other sites More sharing options...
sparky_spit Posted November 2, 2016 Share Posted November 2, 2016 Quoted from RedRooster Mikey have you a megger? a DVM is no good for the insulation test. Good point. A normal digital multimeter won't have a proper megger function, even though it will measure Meg ohms. You need a proper megger which produces a decent amount of volts to test for insulation breakdown.To test it's working, wet both hands, hold a test clip in each and press the button.... Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted November 2, 2016 Share Posted November 2, 2016 Quoted from sparky_spit To test it's working, wet both hands, hold a test clip in each and press the button.... You horrible man..... thought that was what the apprentice was for Nick Quote Link to comment Share on other sites More sharing options...
Hogie Posted November 3, 2016 Share Posted November 3, 2016 Have a look here for a decent Megger http://www.ebay.co.uk/sch/i.ht.....+tester&_sacat=0The ones I used back in the 70's had a cranking handle to get the 1000V's required.Roger Quote Link to comment Share on other sites More sharing options...
RedRooster Posted November 3, 2016 Share Posted November 3, 2016 We have 5KV ones at work, they make big sparks Quote Link to comment Share on other sites More sharing options...
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