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Old 03-14-2013, 09:09 PM
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Ford 302 HEI / solenoid help

Brand new to this forum and it seems I've found a good one! My 302 engine in my Model A came out of a 1970 Ford F100. I just bought the small cap HEI distributor which does not have the coil built in. I also bought a new Ecore style coil. I connected the red wire from the distributor to the + on the coil and the other to the -. I also ran another wire from the + on the coil to my ignition switch. My question is, what wires do I run to the "S" and "I" terminals on the solenoid? I have a new wiring harness and just started wiring the car up. Any help would be much appreciated.

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Old 03-16-2013, 10:08 AM
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The main question is: do you need a ballast resistor in the coil circuit?
The current that flows through the coil must be limited by something. In 1970 point type distributors were used and a ballast resistor controlled current in the coil.
HEI distributors usually have the current controlling circuitry built in but this will need to be confirmed. Consult the paperwork that came with the new distributor or post the brand and cat# here. Or GOOGLE it.
The S terminal on the solenoid is for start. This terminal connects to the start terminal on the ignition switch via the neutral start safety switch.
The I terminal will not be used if the HEI has coil current control. However, it's probably not the case but if an external ballast resistor is required the I terminal will connect to the coil + terminal. This system will bypass the ballast resistor during starting.

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Old 03-17-2013, 07:11 PM
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Vic's spot on....... With a points/coil type system the coil only needs 9-ish volts or it will burn up in short order. The ballast resistor or resistance wire drops the 12v from the ing switch to 9-ish volts etc...... some when running the coil won't burn up.

When starting the coil uses a full 12v to aid in starting it gets it from the "I" terminal on the relay, when the key is in the start position the starter relay energizes and the sends a full 12v out thru the "I" terminal.

Some say you do not need this "I" terminal hookup......... and if your car starts fine without it, you probably don't...... however your ing switch has to provide pwr to the ballast resistor while in run and start.
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