Alfa Pages :: Topic review

Eddie_W · Posted: Tue Apr 15, 2008 4:24 am Post subject:

A ballast resister works in the reverse to your description. It is used with a lower voltage coil and reduces the 12 volts to whatever is the correct voltage for the coil when the motor is running. In startup mode the ballast is bypassed thus putting a full 12v into the lower voltage coil with a consequent jump in spark energy. This also compensates for any voltage drop due to starter drain.
It all starts with the ignition key. With the key in start position the coil is supplied with 12v, with the key in run position the coil is supplied via the resister.
Most Jap manufacturers used a resister block near the coil, early Fords used a resistance wire from the key.
Most electronic ignitions like a MINIMUM of 12 v to work properly and won't produce a decent spark without. I haven't taken that close a look at the Alfa setup but a quick check of the voltage rating of the coil will indicate if a resister is necessary.
There is supposed to be a danger of overheating a coil with a voltage higher than its' rating but a friend of mine ran a racing Mustang on the road for a number of years with a 6v coil and had no problems.
Hope this helps
Regards eddie

knighty

as some of you know I have just put a 118bhp 1.7 8v into the back of my beach buggy, it is a hydraulic head version and I'm told it was from an 1989 G-plate sud......I am hearing stories that some cars are fitted with a ballast resistor that cuts the coil/amp voltage down to 9v when starting, then once the engine is running it switches over to 12v.......or something along hose lines......if you dont have this ballast resistor it will fry the coil or ignition amplifier and cause a load of grief......now I dont yet have this problem.......I'm just worried it might happen to me, should I be worried?

I have run a 1.5 sud motor for the past 4 years and that had electronic ignition (from what I can see) and all has been fine.......am I worrying about nothing?