C1 Ballast Resistor Options

[Florian W.]

Based on several of the earlier posts, it seems that my '60 Fuelie should have a 0.3 ohm ballast to match with its 107 coil. It currently has some sort of repo ballast with a resistance of about 2.3 ohms at 60 degrees. The repos that I see to replace the original 1931385 D1111 Delco part are marked as 0.2 ohms and lack the break-off tang of the original (and maybe other features that I don't know to look for). Strangely enough, the two claimed NOS D1111 ballasts that I found didn't have the break-off tang, either. Are these repos as close as I can reasonably get without scouring salvage yards and swap meets, or is there hope of running across an NOS part with all the right features?

Thanks,
Lee

[Jack H.]

Re: C1 Ballast Resistor Options

There's a 'hope' but bear in mind, the tear-away tab feature ceased in GM production somewhere in the '66-68 time frame. So, your 'NOS' part has to pre-date that in terms of its manufacture date.

Nope, to my knowldege, there's NOBODY making a correct reproduction of the part--expect to take a minor deduction on 'Configuration' for the reproduction part's deviation from older factory originals.

You have really two alternatives:

(1) Modify the reproduction to 'appear' to be a factory original (that mean's re-working the mounting tab end with a milling machine to re-create the tear-away tab and then re-plating the tab.

(2) Find a correct original from a donor car. But, as far as Chevy's go, you're looking at sourcing one from a turbo charged Corvair, 348 solid lifter or 409 passenger car. These guys typically 'lie' and say they've got a lowly 'Corvette' when they want the part!!!

[Roy B.]

Re: C1 Ballast Resistor Options

In time you can locate one on e-bay but you need to know the (look) of the original design when looking and don't go by the part number. Many other cars used the same part but use a different part number. I found this one nos in a box for $5.00 under Cadillac.

I've posted pic's showing the correct DESIGN for 55's trying to show people what the original design is and don't always go by a sellers part number. This is the 55 Corvette

[Florian W.]

Re: C1 Ballast Resistor Options

Jack, Roy,

Thanks for the info - that certainly explains why these NOS parts are missing the tear-off feature. Since the repo is not much money, I think I'll go that route. At least it will get the resistance value closer to what it should be with my setup and I can always keep looking for an original part.

Regards,
Lee

[Florian W.]

Re: C1 Ballast Resistor Options

So much for Plan A. The repo I received looked nothing like the web site photo: it lacked the "C" cutout on the strap and the ends of the ceramic had no notch by the terminals. Rather than being the advertised 0.2 ohms, it measured over 3 ohms. Other than that, it was perfect.

I guess I'm back to the search.

Lee

[Jack H.]

Re: C1 Ballast Resistor Options

Be careful when you measure resistance to verify!

If you're using a run of the mill VOM without an insertion zeroing feature, the intrinsic resistance of your probe leads can 'swamp' the reading you're taking...

At this low of a resistance (ballasts run 0.3 to1.8 ohms), you're PUSHING the native precision and dynamic range of most VOM's!

[Roy B.]

Re: C1 Ballast Resistor Options

My understanding is that a resister that had no notch on the ceramic and no (C) cutout on the strap was the first design .

Later resister still having no notch on the ceramic but now has a (C) cut out on the strap is a later C1 second design . Is that correct??

[Richard M.]

Re: C1 Ballast Resistor Options

Be careful when you measure resistance to verify!

If you're using a run of the mill VOM without an insertion zeroing feature, the intrinsic resistance of your probe leads can 'swamp' the reading you're taking...

At this low of a resistance (ballasts run 0.3 to1.8 ohms), you're PUSHING the native precision and dynamic range of most VOM's!

Bingo!

If one is using a low grade meter you probably have a large instrument error at the start. Not too many people have a Fluke 4 wire Kelvin ohm meter around these days. I used these in my early days at Raytheon where each test lead had 2 isolated pins. When contacting the connection, it then shorted each pin pair in each lead, yielding very accurate resistance values.

http://www.allaboutcircuits.com/vol_1/chpt_8/9.html

When set on the lowest scale using your typical $10 Auto Zone handy dandy meter(or equivalent), short your 2 test leads together and see what you read. I suspect 0.2 or more ohms. Subtract that from the actual reading on the part.

Rich

[Mike M.]

Re: C1 Ballast Resistor Options

My understanding is that a resister that had no notch on the ceramic and no (C) cutout on the strap was the first design .

Later resister still having no notch on the ceramic but now has a (C) cut out on the strap is a later C1 second design . Is that correct??

your understanding is correct.mike

[Roy B.]

Re: C1 Ballast Resistor Options

your understanding is correct.mike

Thanks , some times I"m correct , you heard anymore about the 55 JM.?

[Florian W.]

Re: C1 Ballast Resistor Options

I haven't felt this stupid since those EE classes I snoozed through right after that Edison guy gave us the light bulb. Realizing that we are dealing with low resistances, I checked our ballast with two different meters to obtain essentially the same readings. These meters are far from the last word in accuracy, being just Craftsman's version of a basic Fluke DVOM. But in my simple world, when you touch the probes together prior to taking your measurement, you should get a zero reading because the meter to some degree is able to compensate for the resistance in the probe leads. Have I been wrong (again) all these years?

Lee

[William C.]

Re: C1 Ballast Resistor Options

On a slightly different point, there are a number of directives to dealers via service pulletins regarding the perils of using the low resistance ballast resistor in a street driven car. Poor points life is usually the topic and the recommended fix is to go to the "standard" high resistance ballast resistor. Just a thought if you plan on driving the car.

[Jack H.]

Re: C1 Ballast Resistor Options

Depends the specifics of the meter... Your typical Fluke with auto-lead zeroing feature has a 'REL' button.

To activate you put the meter into resistanace mode, touch the leads together and while holding them together, hit the REL button.

The accuracy of this method depends on the specifics of the meter itself. Most employ consecutive sample and display technology which makes the integration constant of the meter's sampling function CRITICAL to the accuracy.

Just, placing the probes across a given resistance will result in different displayed resistance values from sampled reading to reading. And, as you 'push' these meters to their accuracy limits that variance can be significant.

In the case of the ballast resistor, we're reading a load value that's essentially on par (magnitude) with the intrinsic resistance of the probe wires. That's where the 'trick' lies in getting an accurate reading.

What you'd really like is an analog ohm meter with a 0-5 or 0-10 ohm scale. Unfortunately, these critters are rather rare!

For a reasonably accurate alternative approach, connect a low voltage, regulated bench DC power supply to the resistor (say 2 VDC) and measure the current that flows. Then, work backwards (E=IR) to compute the resistance of the ballast.

Or, put connect the ballast in series with a LARGER resistance load. Then, hook the two to a regulated DC power supply and measure the voltage dropped across the ballast as well as the voltage dropped across the larger series resistor and work backwards to compute the resistance of the ballast via voltage divider action...

[Duke W.]

Re: C1 Ballast Resistor Options

On a slightly different point, there are a number of directives to dealers via service pulletins regarding the perils of using the low resistance ballast resistor in a street driven car. Poor points life is usually the topic and the recommended fix is to go to the "standard" high resistance ballast resistor. Just a thought if you plan on driving the car.

The 0.3 ohm ballast pushed primary current to the limit and was tough on points.

Higher primary current produces more spark energy, which helps fire fouled plugs, but if your engine is in good tune with proper heat range plugs (AC heat range 5 or equivalent for normal road driving) and you don't drive short trips only, they should stay pretty clean, so use of the 1.8 ohm ballast might save you from being stranded as I once was when the points on my SWC burned so bad it would not start.

The problem is worst in cold weather because the ballast's resistance decreases with temperature. One of the TSBs actually recommended swapping the 0.3 ohm ballast for a 1.8 ohm during winter.

I wonder how many owners actually did that?

Duke