Ballast resistors

Should these be used along with 12v coils ? As I know the original Magneti Marelli coils where 9v and wired up to a ballast resistor. All to ensure best possible spark during start-up.

Last year I removed the points in favor of the Pertronix Ignitor combined with Pertronix 40Kv coils. The new coils are 12v 1.5 Ohm but non the less I was recommended by Pertronix Tech to keep using the resistors. Found their answer a bit uncertain and started to think about this again now that I'm having a bit of trouble with the ignition. I have asked Pertronix once again and his time they recommend NOT using these coils combined with resistors.

It would be great if I could get any advice or inputs from members here in this matter.

Thanks,
Arvid

 

Ross,thank You. I've checked the wiring provided by Pertronix and they show two alternatives both with and without resistors.

I think I have resolved the problem. I had hooked up the positive lead to the Ignitor on the wrong side of resistor. Combustion and spark seems far better now and exhaust temp is normal.

Further tuning tomorrow

 

Dèsolè Christopher.

Thank you Simon. I must add this to my blooper account and move on. I hope You soon resolve your engine issues. I know how frustrating things can be.

 

Ross, the resistors are fed continuous 12v by a yellow lead from ignition key. There is also a red positive leads that go on the other terminal of the resistor,this one comes from a relay and deliveres 12v at start up. And there is where I got mixed up... I think this relay is engaged with the starter motor and only deliveres 12v at start-up. As I've read its purpose is to deliver 120-130% the normal voltage to the original 9v coils to aid start-up.

I had hooked the feed to the Pertronix Ignitor on the red terminal of the resistor,not the yellow (red equals +12v right ? No,not this time). There must be a difference in voltage on these terminals when engine is running since it clearly is sparking more even. I have not measured voltage yet but will do so today,then it all hopefully becomes logical.

My thoughts are that this has affected the signal from the Ignitor and therefore again affected the spark delivered from coil. Im still concerned about voltage to coils and that I might remove the ballasts all together. There is also an advice from Pertronix that the resistance between battery negative and engine/distributor should not exceed 0.2 ohm. For now I have 0.5 ohm and that may reflect that the engine-chassis strap needs renewal. This also needs to be checked and measured.

I'll just have to see what this day brings

 

Ok,measures done. Coil has 10.6v fed from ballast with engine running. Certainly not optimal and for sure not correct. I'm re-routing the feed to coil to the other terminal on ballast which is fed directly from ignition key/battery.

In addition Pertronix gave a final answer that the ballasts should not be used since this coil is internally resisted. So now there's no doubt how to wire it up.