[C2] Ballast Resistor on the SBC
02-28-2018, 03:21 PM
#1
Drifting
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St. Jude Donor '09 & '11
Ballast Resistor on the SBC
I'm replacing the stock distributor on my 65 327 with a pro billet HEI distributor. Should I remove the ballast resistor from the circuit or does it have to stay? What the heck does it do anyway?
02-28-2018, 04:19 PM
#2
Team Owner
The ballast resistor is bypassed during startup but engaged while running, it helps reduce the wear on ignition components. I don't know if you keep it or not with HEI. I would never swap out an original distributor for an HEI anyway...
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TCKT B8 (02-28-2018)
02-28-2018, 04:55 PM
#3
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You might ask the seller of the HEI distributor to be sure, but I'm pretty confident that you don't need a ballast resistor with the HEI.
As Frankie said, it's there to reduce wear, chiefly on the points. It does that by limiting the amount of current that passes through them.
As Frankie said, it's there to reduce wear, chiefly on the points. It does that by limiting the amount of current that passes through them.
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TCKT B8 (02-28-2018)
02-28-2018, 07:17 PM
#4
Drifting
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Absolutely get rid of the ballast resistor - it will cut your spark energy in half...
I had a hell of a time getting my brand new crate motor tuned last year (I ran an HEI unit and Flametrower III Coil) until I took a deep breath and thought about it...bypassed the ballast resistor and it runs awesome.
I had a hell of a time getting my brand new crate motor tuned last year (I ran an HEI unit and Flametrower III Coil) until I took a deep breath and thought about it...bypassed the ballast resistor and it runs awesome.
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TCKT B8 (03-01-2018)
03-01-2018, 01:13 AM
#6
Drifting
As stated above, you don't need the ballast resistor. Not sure in your case, but an HEI I installed in another car said in the instructions that the voltage feed should be a 10 gauge wire, so the current requirement is fairly high.
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TCKT B8 (03-01-2018)
03-01-2018, 07:45 AM
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Team Owner
03-01-2018, 05:57 PM
#8
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So, here goes:
The coil is fed by 12vdc during the starting cycle thru the solenoid. Increasing the spark to the plugs temporarily.
Upon starting (once running), the coil is fed less than 12vdc thru the ballast resistor,
originally to reduce wear on the points to improve their life span.
All electrical devices are designed for specific voltage and amperage. So, if a full 12vdc is applied to the stock coil all of the time, I would think the life of the coil will be shortened due to increased internal heat and break down of the insulation on the windings. Probably not enough life loss to be noticed on a classic car driven only a few miles a year.
Many car manufacturers changed coil design when they changed to HEI / electronic ignition.
The coil is fed by 12vdc during the starting cycle thru the solenoid. Increasing the spark to the plugs temporarily.
Upon starting (once running), the coil is fed less than 12vdc thru the ballast resistor,
originally to reduce wear on the points to improve their life span.
All electrical devices are designed for specific voltage and amperage. So, if a full 12vdc is applied to the stock coil all of the time, I would think the life of the coil will be shortened due to increased internal heat and break down of the insulation on the windings. Probably not enough life loss to be noticed on a classic car driven only a few miles a year.
Many car manufacturers changed coil design when they changed to HEI / electronic ignition.
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TCKT B8 (03-02-2018)
03-01-2018, 07:51 PM
#9
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2023 C2 of the Year Finalist - Unmodified
2019 C2 of Year Finalist (stock)
2015 C2 of the Year Finalist
Dan
03-02-2018, 09:40 AM
#10
Melting Slicks
The resistor has to go. As suggested, you need to run a heavier gauge wire between the fuse panel and the distributor. At a minimum 14 ga.
Very easily done, very easily hidden.
Did this on my '71 years ago. Looks like it was made that way.
Carter
Very easily done, very easily hidden.
Did this on my '71 years ago. Looks like it was made that way.
Carter
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TCKT B8 (03-02-2018)
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TCKT B8 (03-03-2018)
03-03-2018, 10:56 AM
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Good job. I would embellish this with one clarification, a full 12 V is always applied to the coil whenever the primary circuit is closed. It is the current that is retarded (can I say that?) through the circuit via the ballast resistor which prevents as you observed, a degradation of coil winding insulation integrity over time and less pitting of the breaker contact surfaces.
Dan
Dan
03-03-2018, 04:06 PM
#13
Drifting
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St. Jude Donor '09 & '11
I ran a new 14 gauge wire today and got rid of the ballast resistor. I was really pleasantly surprised with the results - it runs significantly better! Better throttle response and more power. I have not yet installed the new distributor - maybe no need. Currently running the stock tach drive distributor converted to a Unilite electronic ignition.