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Is the FB coil a ballast coil?

I've replaced the points with an electronic ignition and "standard" 3 ohm coil. Starts ok and runs for two minutes or so then starts missing under load, backfiring etc. is this because I should have a ballast coil with 1.5 ohms? Thanks in advance.

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the coils your problem not enough voltage
electronic ignition doesnt run a ballast resistor

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Is it HEI? start by checking the voltage at the positive terminal of the ignition coil - ign to on - for electronic ignition it needs to be full 12V - not 8-9V ...if you have less than 12V that's your starting point to address... if you have installed a pertronix system for a 6cyl for instance the 3Ohm coil is what you need..but if you only have 9V at the positive because you have ballast resistance already in circuit you will have a weak spark..the FB should have originally been 3Ohms..ie not an R coil..

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Andrew

Will check

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FB with mags, rust and attitude. Holden Heaven.

Early Holdens supply a full 12 volts to the coil through the starting circuit if they are all the same as an EH.
Once the motor has started and the key returns to the normal running position, the current is directed through a resister wire to the coil, which reduces the running voltage to 9 volts.
To get around this, you can replace the resistance wire from the ignition switch to the coil with a normal wire, or put a relay in the circuit to supply a full 12 volts at all times.
Also, to get the maximum benefit you need to change to spark plugs designed for electronic ignition. Can anyone supply a number for these?
Information you need, including relay wiring, is here: http://holdenpaedia....
David

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Old is good.

that I have show the parallel resistance wire you mention above was first introduced in the EJ. Prior to that the coil received full 12V so the coil had the higher 3 Ohm primary resistance compared to the lower 1.5 Ohm that came after and relied on the resistance wire to drop the voltage to 9V. But who knows what may have been done on an old car so its best to measure what you have to start with. It eliminates all assumptions. Many of the electronic ignitions still specify the 3 Ohm resistance to reduce the current through the switching module...so you also need to know what unit has been fitted..the symptoms described though are typical of not enough voltage to the coil...

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Andrew

Great info

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FB with mags, rust and attitude. Holden Heaven.

I will check

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FB with mags, rust and attitude. Holden Heaven.

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