ballast resistor

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ballast resistor

Postby hbr341 » Thu Nov 14, 2019 7:33 pm

Hi All
Ive been rebuilding my 1968 HB OHV having issues with the ballast resistor getting very hot had the ignition on to set up the timing and smoke started to come from it, Got the car running and again the resistor almost caught fire I took the wire off it and off the solenoid the car still started fine without it I thought it only worked as the starter motor operated anyone got any advice please.

Regards Chris.
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Re: ballast resistor

Postby droopsnoot » Fri Nov 15, 2019 10:50 am

If it's like a HC, then the opposite is true - the ballast resistor (it's in the loom on a HC) is running all the time *except* when cranking / starting, and during that time there's a by-pass wire from the starter motor that delivers the full voltage to the coil.

No idea why it would get so hot - it'll always get a bit warm because the drop in voltage has to go somewhere. Can you measure the resistance across it, in case that gives someone any clues? If you have the ignition on for a long time without the engine running, I have heard that would cause the coil to get warm, so maybe it's something to do with that. Maybe it had just reached some critical point when you started the car.

I'm not surprised it's running with the resistor bypassed, but it may shorten the life of your coil if you run it at the full 12v if it isn't designed for it.
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Re: ballast resistor

Postby jpsmit » Fri Nov 15, 2019 2:35 pm

I always have a tough time visualizing electrical issues - but, is there any chance the coil has an internal resistor?
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Re: ballast resistor

Postby Fred Dukes » Fri Nov 15, 2019 6:45 pm

I suspect a low resistance coil - simple substitution test may give you a clue with another coil :goodideasign:
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Re: ballast resistor

Postby hbr341 » Mon Nov 18, 2019 8:22 pm

Hi
Thanks for your help as the car starts fine and runs fine I will not bother with it.

Regards Chris.
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