Ballast resistor ?
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Joined: Nov 2002
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From: State College PA
Ballast resistor ?
I have a delco-remy ballast resistor that has a 1.78 written in pencil on the side. No other numbers or anything on it. Anyone know what the deal is on these or which car(s) it's for? Thanks!
Team Owner
Joined: Oct 2000
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From: Washington Michigan
Re: Ballast resistor ? (GOPSU!)
All pre-'68 Corvettes (and Chevy passenger cars) used them between the ignition switch and the coil so the coil only ran on 7-8 volts, to minimize burning of the points. The 1.78 is probably the measured resistance of that particular resistor. They were 0.3 ohms until mid-'64, when they changed to 1.8 ohms. :thumbs:
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Re: Ballast resistor ? (JohnZ)
I can't speak for pre-'63 models, but in early '63 all engine options were equipped with the 0.3 ohm ballast. In a running change, 250 and 300 HP engines were switched to the 1.8 ohm ballast (due to customer complaints of burned points, as John pointed out), and SHP/FI engines continued with the 0.3 ohm ballast. The lower resistance ballast provides higher primary current for high ignition energy, but is tough on points.
This utilization continued through the '64 MY, but beginning in '65 all engines with the single point ignition used the 1.8 ohm ballast.
Both ballasts look the same. The only difference is the wire resistance, so they can only be differentiated by measuring them with a sensitive ohmeter.
BTW the '63 NCRS JG is incorrect on ballast untilization. Don't know about the '64 JG.
Duke
This utilization continued through the '64 MY, but beginning in '65 all engines with the single point ignition used the 1.8 ohm ballast.
Both ballasts look the same. The only difference is the wire resistance, so they can only be differentiated by measuring them with a sensitive ohmeter.
BTW the '63 NCRS JG is incorrect on ballast untilization. Don't know about the '64 JG.
Duke
Melting Slicks
Joined: May 2002
Posts: 2,225
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From: Penticton B.C. Canada
Re: Ballast resistor ? (SWCDuke)
I don't know whats wrong, but I have just always assumed that when you have a ballast resistor inline in the run circut you have a volatge drop to 8? volts. Never checked before. I have an old tractor converted to 12v. In the run circut I installed a napa ballast resistor for a mid '60'sGM. Because the dist on this tractor is in a terrible place I wanted to be sure and measured the voltage at 'run'. Full voltage. Measured the resistance, 2.3 ohms. Went and bought a ac/delco resistor. Checked it 1.8ohms. Installed it, full voltage on run circut! So I just installed both resistors in line and hope for the best. The wiring is very simple in this thing, it's not picking up voltage amywhere else. It's doesn't even have a 'start' circut.
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Re: Ballast resistor ? (GaryC)
The JG has the wrong utilization, but I don't recall the details off hand. I don't know "why" it's wrong - someone made a mistake when writing up that section.
The JG does not state the proper ballast utilization as started in the AIM and change history for that page. The AIM is also backed up by a TSB.
Duke
The JG does not state the proper ballast utilization as started in the AIM and change history for that page. The AIM is also backed up by a TSB.
Duke
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Melting Slicks
Joined: May 2002
Posts: 2,225
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From: Penticton B.C. Canada
Re: Ballast resistor ? (jerrybramlett)
Thanks Jerry;
Doesn't seem like a whole big drop in voltage. All my cars have HEI's so I'm waiting to see a points car somewhere. I'll be right on it to check what it's doing. Up utill now it seems that the common knowledge has been that the voltage to the points drops to 8ish volt range thru the resistor on 'run'.
Doesn't seem like a whole big drop in voltage. All my cars have HEI's so I'm waiting to see a points car somewhere. I'll be right on it to check what it's doing. Up utill now it seems that the common knowledge has been that the voltage to the points drops to 8ish volt range thru the resistor on 'run'.
Le Mans Master
Joined: Feb 1999
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From: Mobile AL
Re: Ballast resistor ? (00fxd)
Nah, but it could be that low under certain conditions (500 rpm idle, lights on, weak battery, etc.).
I measured the voltage at the coil with a .3 ohm ballast resister and a stock generator on a running (2000 rpm) '59 Corvette engine. It was around 11 volts.
I measured the voltage at the coil with a .3 ohm ballast resister and a stock generator on a running (2000 rpm) '59 Corvette engine. It was around 11 volts.
