72 Lt-1

[72LT-ONE]

I'm not if my 72 LT-1 has a ballast resistor or not. Does anyone know what year they stopped using them? Is it the year Chevy switched to electronic ignition?

Thanks,

Mike

 

[Stallion]

The first Vette to have HEI was the '75. Is that what you are asking?

 

[72LT-ONE]

res.

The first Vette to have HEI was the '75. Is that what you are asking?

I'm just wondering if my 72 had a ballast resistor.

M

 

[Hib Halverson]

72s have ballast resistors.

Electronic ignition (called transister ignition) was an option back then, however, even if the car has T/ign., it will have a ballast.

 

[JohnZ]

'67 was the last year for the separate ballast resistor on the firewall; the cloth-covered resistance wire replaced the ballast resistor in 1968. T.I. cars didn't use a ballast resistor.

 

[72LT-ONE]

Thanks Guys...I was in the process of eliminating the points in my 72 and the positive side of the "Ignitor" had to be connected before the ballast resistor. All is well now.

Thanks again

M

 

[Stallion]

Now I'm confused. I don't understand exactly what this ballast resistor is for and why it was stopped and what it was replaced by? :confused

 

[JohnZ]

TR, on pre-HEI cars that used points, the coil was designed to operate continuously at 7-8 volts, not the 12 volts the electrical system provides; from '55-'67, a ceramic-encased wirewound ballast resistor that mounted on the engine side of the firewall was used in the circuit from the ignition switch to the coil to reduce the voltage to that component, except on cars with K-66 Transistor Ignition (that system incorporated resistance in its wiring harness). From '68 through '74, the separate ballast resistor was replaced by a special resistance wire for the feed circuit from the ignition switch to the coil - it was identified by its woven white cloth heat-resistant covering. That's why pre-HEI cars have a second wire connected to the coil (+) terminal - it comes from the starter solenoid, and supplies a full 12 volts to the coil only when the starter is cranking, for faster starting. When HEI came along in '75, the resistance was no longer required, as the HEI distributor and integral coil operated on a full 12 volts.

 

[Stallion]

Ah, I see. Thanks a lot, John. I was wondering about that extra wire when I was working on my buddy's old Impala. But now I know!

 

[bossvette]

This may throw some confusion but I seem to remember you could get coils with the ballast resister in it that cut down the voltage to the points, which was what required the lower voltage to cut down on wear. And as John said when points were eliminated either with the HEI or transistor ignition the ballast resistor was eliminated. Points were a carry over from the days of 6 volt systems which were standard untill sometime in the 50's
Now a days some of the ignition systems wont run unless you have 12.5 volts or better. Some of the hotter systems are playing around with 16 volts and dual terminal batteries.

:L I can see some of you young guys saying "6 volts, whats that?":L