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new here and hoping based on what I've read from some of the folks responses and vast knowledge i can gain some solid advice or insight on a few issues i'm having with my 67 Duetto. A little history on the car. I bought it several months back, not 100% restored but overall in great shape though I've had issues from literally day one with the carbs running too rich and stalling out. have since rebuilt the carbs and had them tuned and then the next issue was while driving the car, about 4 miles out, the ignition coil was getting too hot and causing the car to shut off. installed new bosch blue coil and the same thing happened, car died after driving about 10 miles. though it's not supposed to be needed with this coil, mechanic decided to put a ballast resistor in place, which has helped but I can feel the car have issues on take off after stopping at stop signs or traffic lights. the other day, going to start the car, tried to crank it but the battery was dying, jumped it off, started and ran fine. went to star the car last night and battery worse than before and almost completely dead.
i haven't had time to run through electrical with ohm meter but first off wanted some advice on ignition coil and resistor and if this could have something to do with the battery issue? Also, any ideas on what could be causing the coil to get too hot in the first place? i've read about grounding issues and this doesn't seem to be the case. With there being very limited amounts of electrical items on this car i'm curious on thoughts related to ignition coil, resistor and battery dying.
thanks in advance

jojo
 

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You're right, you shouldn't need a ballast resistor with a Bosch blue coil. And, the coil shouldn't run hot.

All I can think of that would combine a hot coil with a failing battery is an over voltage condition: a bad voltage regulator delivering voltage in the high teens, cooking the coil and battery. Since there is nothing solid-state on a '67 Duetto (I assume your's still has points), there isn't a lot that will go bad when the voltage is too high; try that with a modern car and everything will fail. Usually when you kill a battery with too much voltage, you get an odd odor from the battery acid boiling. Smell anything funny?

A quick check would be to put a voltage meter across the battery terminals while the engine is running (say at 2,000 rpm). It should measure ~13 to 13.5V. A reading appreciably above that would explain your symptoms.
 

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You're right, you shouldn't need a ballast resistor with a Bosch blue coil. And, the coil shouldn't run hot.

All I can think of that would combine a hot coil with a failing battery is an over voltage condition: a bad voltage regulator delivering voltage in the high teens, cooking the coil and battery. Since there is nothing solid-state on a '67 Duetto (I assume your's still has points), there isn't a lot that will go bad when the voltage is too high; try that with a modern car and everything will fail. Usually when you kill a battery with too much voltage, you get an odd odor from the battery acid boiling. Smell anything funny?

A quick check would be to put a voltage meter across the battery terminals while the engine is running (say at 2,000 rpm). It should measure ~13 to 13.5V. A reading appreciably above that would explain your symptoms.
great, what i was looking for to get starting. Yes car still has points and nothing smelled odd and battery definitely not boiling over. Let me check volts and circle back. thanks for getting me started on the hunt
 

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@Alfajay one question on the ignition coil. If the resistor is not needed on the blue coil does having one (actually 2 since the coil already has one) hurt or potentially cause other issues having one when it's not needed? (that is if the car is running propoerly in the first place)
 

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A ballast resistor + a 3 ohm coli will produce weak sparks, particularly during starting and at higher rpm. The Marelli coil + ballast resistor is well engineered. If you think that your existing coil is weak then you would be better replacing it with a Bosch red coil and keeping the ballast resistor and associated wiring.

Check your points gap and if possible measure the dwell angle which should be 60 degrees. The coil will overheat if the dwell angle is too big
 

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The coil will overheat if the dwell angle is too big
Good suggestion! That might also explain the poor running ("I can feel the car have issues on take off after stopping at stop signs or traffic lights"). It doesn't explain the dying battery, but it's certainly possible to have two, unrelated problems going on simultaneously. Especially with a new acquisition.

alfajojo said:
If the resistor is not needed on the blue coil does having one (actually 2 since the coil already has one) hurt or potentially cause other issues
As alfaparticle wrote, having too much resistance would result in a weak spark and potentially poor running. But it wouldn't make the coil run hot or drain your battery.
 

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Other threads have discussed the issue of how an oil filled coil is mounted, with the recommendation of installing it vertically to avoid overheating. Could that be the issue here? I did run a Bosch blue coil for a while , I think it was horizontal, and I never had any misfires and wasn't aware of any overheating.
 
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