C2 Ballast Resistor

[Richard S.]

I am looking for information on the ballast resistor for my 63 340 HP car. Appreciate any information on the nominal resistance and any supplier that provides such a part. Coil on the car is an 091. Stock point system.
Thanks
Rich

[Harry S.]

Re: C2 Ballast Resistor

I am looking for information on the ballast resistor for my 63 340 HP car. Appreciate any information on the nominal resistance and any supplier that provides such a part. Coil on the car is an 091. Stock point system.
Thanks
Rich

Rich, I suggest you look for an original (NOS) resistor with the Black dot for SHP as opposed to the blue line for the 250/300 hp cars.

Think it's part number 1931385

[Harry S.]

Re: C2 Ballast Resistor

Found this, from John.............

You can follow the usage trail through the Assembly Manual and NPC's (Notice of Production Change) - it goes like this:

'56 - Early '63 all used the #1931385 (0.3 ohm) resistor; carbureted cars used the #1115091 coil.

TSB #DR-577 (2/27/63) described the February 4, 1963 production change at St. Louis to the new #1957154 (1.8 ohm) resistor on all 250hp and 300hp engines, " to eliminate point burning during cold-weather operation". The #1115091 coil continued on all points applications. It also noted that the Service parts would be identified with a black dot (for the old 0.3 ohm resistor) and with a blue stripe (for the new 1.8 ohm resistor).

The #1957154 (1.8 ohm) resistor continued to be released for 250hp and 300hp engines for 1964 start of production, with a new coil (#1115087).

NPC 307 and 328 released the #1957154 (1.8 ohm) resistor on 1/3/64 for L-76 (365hp) and L-84 (375hp) engines, replacing the #1931385 (0.3 ohm) resistor, along with the #1115087 coil, replacing the #1115091. For the rest of the '64 model year, all Corvettes with point ignition used the same resistor (#1957154) and the same coil (#1115087).

For '65 (and through 1967), all Corvettes with point ignition used the 1.8 ohm resistor, but the #1115087 coil was replaced by the #1115202 coil.

K-66 Transistor Ignition-equipped Corvettes didn't use a ballast resistor; the T.I.harness had a built-in length of special resistance wire instead.

In '68, the ballast resistor disappeared, and was replaced by a length of woven fabric-covered special resistance wire from the fuse block to the coil that served the same function until 1975, when the HEI ignition system was introduced, powered by a full 12-volt feed circuit.

[Richard S.]

Re: C2 Ballast Resistor

Harry
Thank you for the detailed notes. Greatly appreciated.
Rich

[Robert I.]

Re: C2 Ballast Resistor

When did Corvettes stop using ballast resistors? Should I carry a spare with me on my 62 340 hp car?

[Tim G.]

Re: C2 Ballast Resistor

My 1967 gave me fits recently, the car ran poorly when it warmed up but ran fine when cool. I traced it to a cracked ballast resistor. You can always take the bottom wire and connect it directly to the top wire in a pinch. That was the way I diagnosed the issue. I bought a used one from a friend and it works great.

[Ed S.]

Re: C2 Ballast Resistor

I purchased 2 ballast resistors for my 64 L76 from "Schafer Classic Reproductions" - Schafer was recommended by someone in another thread some time ago. These resistors are dead on in appearance and functionality. Did an ohm resistance check on both - right dead center of the recommended range. Here is the link to their website. https://shafersclassic.com/c-1164629...ted-parts.html

[Richard M.]

Re: C2 Ballast Resistor

I always carried a spare ballast in my '59. A Napa version is cheap insurance.

I also carried points, condenser, VR, belts, lamps, hoses, tools etc.

[Mike M.]

Re: C2 Ballast Resistor

ed; I VIEWED THE BALLAST RESISTORS OFFERED BY SHAFERS. their porcelain portion lacks the cut outs , hence your 64 will get a minor deduct. the cut outs appears in the mid-63 model year corvettes. mike mccagh

[Richard S.]

Re: C2 Ballast Resistor

Bob
Not sure about when ballast resistors stopped being used. But at least to 1967.
Rich

[Duke W.]

Re: C2 Ballast Resistor

A resistance wire in the harness replaced the external ballast resistor beginning in 1968.

Failure of the ballast is rare, so I don't see a need to carry a spare, but models with the 0.3 ohm ballast could burn points, especially in cold weather. It happened to my SWC once back in the sixties. Chevrolet wrote a TSB on the issue.

A functioning set of points that you replace due to mileage makes a good spare. Set the dwell angle to 30 before you remove them and it should be the same, as will be the initial timing, if you have to swap in the spare to get home.

Duke

[Leif A.]

Re: C2 Ballast Resistor

If memory serves correctly, the '53 - '67 Corvettes used a ballast resistor, the '68 - '74 Corvettes used a resistance wire and the '75 and later Corvettes eliminated the ballast resistor and resistance wire altogether.

[Richard M.]

Re: C2 Ballast Resistor

ed; I VIEWED THE BALLAST RESISTORS OFFERED BY SHAFERS. their porcelain portion lacks the cut outs , hence your 64 will get a minor deduct. the cut outs appears in the mid-63 model year corvettes. mike mccagh

Mike, Do you mean this cutout? (Pencil tip area)

These are the 0.3 ohm versions. (missing the metal punchout tab though)

[Gary B.]

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[Richard M.]

Re: C2 Ballast Resistor

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Yes must be. I remembered the tab, but not the porcelain.

Rich