Which Coil?

StefanVXR8

StefanVXR8

Member
Hey guys,

My car has a Piranha electronic points system fitted and as part of some general maintenance I replaced the old coil, plugs and leads with new ones, specifically the coil was an NGK U1056.

Since I replaced the coil (and stupidly disposed of the old one) the car has had a few runnings issues such as loosing power under load, misfiring and more recently struggling to start and stay running.

I’m pretty sure it’s not a carb issue as they have both been serviced and it was problematic before and after. Now it doesn’t want to start at all.

Is it possible the coil has always been faulty or the wrong type and what type should it be for an electronic points system? I did find an old user manual for the Piranha system on line and it mentions requiring 12v on the positive terminal of the coil.
 
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The web says its for a series resistor, or ballast system. You should see resistance around 1-1.5 ohms, so try a different setting on your meter. Try to verify that your car has a ballast resistor fitted - voltage across the coil leads (disconnected) should be around 9V, not 12v.
 
Check it across the positive lead to earth, not across the two wires. One of them will go to the points in the dizzy, and may not be fully earthed. Have you checked the condition of the points?
 
Doh, yeah good point. I’ll check again.

No points as it’s been replaced with an electronic system. It used to be OK which makes me think I might have replaced a good coil with a bad one
 
OK, so I’m getting 11v

I wonder whether when the electronic ignition was put in the ballast resistor was bypassed and it actually needs a non ballast coil.
 
Whats the coil resistance? My Lucas DLB101 shows 3 ohm, non ballasted, works fine with points.
 
Oilynuts said:
Hi guys my v8 is a 1971 would this have a ballast coil on it. Also have electronic ignition. Thx.
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I'm sure they all have a 'resistor wire' as opposed to a single ballast resistor. So yes it will be a ballast system, but it's the whole wire that drops the voltage. ....Pink & White from memory. Mine started smoking like crazy when I first started reviving mine - I believe that as they are steel, not copper, so they age poorly. Happy to be corrected!
 
It's probably Eureka wire also known as Constantan wire, which is a Copper / Nickel alloy (it looks like steel). I also am happy to be corrected if not.

Colin
 
The Stealth ignition notes lists the test for ballasted coil supply - remove dizzy connection from coil negative, replace with a lead to chassis, turn on ign, check voltage coil Positive to chassis - if < 80% of battery volts there is a ballast in the positive lead. Mine showed 12.6 at battery, 7.8V tested as above. Correct coil will have a suffix 'R', as in "C80R" or Bosch GT40R.
 
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