Help, ballast resistor 1948 Pontiac

Car has not been started for 9 years. Note: Converted to 12 volt battery and 12 volt ignition coil 15 years ago and run as daily driver until parked.

Tried to fire it up and no spark. Messed around for hours, tried 3 different coils, etc. to no avail. Finally, upon bypassing the ballast resistor I got a healthy spark and car started immediately. (yes, with 9 year old gasoline)!

The resistor (original, I believe) is installed in the negative side of the coil. It goes from the distributor ground to the negative terminal of the coil. The resistor measures approximately 2 ohms, has continuity and is extremely hot after cranking the engine for about 5-10 seconds.

As I said, absolutely no spark with resistor in place, but healthy spark when bypassed.

Question: Can't find any diagrams with resistor in the ground circuit of the coil. All diagrams show resistor wired in the hot circuit between the ignition switch and the positive side of the coil.

Please note that this car was a daily driver nine years ago and nothing has been touched or re-wired since that time. Can't find listing for ballasts at Rockauto and other internet sites.

Thanks you for your attention,

Ivan Vegvary

On Sat, 7 Jun 2014 22:47:13 -0700 (PDT), Ivan Vegvary
> wrote:

>Car has not been started for 9 years. Note: Converted to 12 volt battery and 12 volt ignition coil 15 years ago and run as daily driver until parked.
>
>Tried to fire it up and no spark. Messed around for hours, tried 3 different coils, etc. to no avail. Finally, upon bypassing the ballast resistor I got a healthy spark and car started immediately. (yes, with 9 year old gasoline)!
>
>The resistor (original, I believe) is installed in the negative side of the coil. It goes from the distributor ground to the negative terminal of the coil. The resistor measures approximately 2 ohms, has continuity and is extremely hot after cranking the engine for about 5-10 seconds.
>
>As I said, absolutely no spark with resistor in place, but healthy spark when bypassed.
>
>Question: Can't find any diagrams with resistor in the ground circuit of the coil. All diagrams show resistor wired in the hot circuit between the ignition switch and the positive side of the coil.
>
>Please note that this car was a daily driver nine years ago and nothing has been touched or re-wired since that time. Can't find listing for ballasts at Rockauto and other internet sites.
>
>Thanks you for your attention,
>
>Ivan Vegvary

Does it stay running if you remove the bypass after it starts? I don't
know about a 1948, but most cars had a resistor on the positive side,
but there was a bypass circuit when cranking. The ones I'm familiar
with had the bypass coming off of the starter solenoid or relay, but I
suppose it can be done with the ignition switch too.

Thanks for your reply Bill. Car runs fine without resistor. Very simple circuit. One hot wire to coil (through ignition key). One wire from negative of coil to points. This negative wire has the ballast resistor in series.
By the way, starting is done through a mechanical push with your right toe to engage the starter pinion with the ring gear.
Thanks
Ivan Vegvary

Ivan Vegvary wrote:
> Car has not been started for 9 years. Note: Converted to 12 volt
> battery and 12 volt ignition coil 15 years ago and run as daily
> driver until parked.
>
> Tried to fire it up and no spark. Messed around for hours, tried 3
> different coils, etc. to no avail. Finally, upon bypassing the
> ballast resistor I got a healthy spark and car started immediately.
> (yes, with 9 year old gasoline)!
>
> The resistor (original, I believe) is installed in the negative side
> of the coil. It goes from the distributor ground to the negative
> terminal of the coil. The resistor measures approximately 2 ohms,
> has continuity and is extremely hot after cranking the engine for
> about 5-10 seconds.
>
> As I said, absolutely no spark with resistor in place, but healthy
> spark when bypassed.
>
> Question: Can't find any diagrams with resistor in the ground
> circuit of the coil. All diagrams show resistor wired in the hot
> circuit between the ignition switch and the positive side of the
> coil.
>
> Please note that this car was a daily driver nine years ago and
> nothing has been touched or re-wired since that time. Can't find
> listing for ballasts at Rockauto and other internet sites.
>
> Thanks you for your attention,
>
> Ivan Vegvary

Sounds like it was wired wrong in the conversion.
The common method for wiring would be points grounded, condenser case
grounded, movable contact on point connected to wire&condenser lead.
Wire from those to negative side of coil. Positive side of coil to
ignition switch.

No ballast resistor was/is needed with the original 6 volt system.

When GM switch to 12 volt they actually didn't change the ignition
system much. Still a 6 volt coil on most engines right up until HEI came
about. GM used a ballast resistor for less than a year. They used a
resistor wire most of the time.
The resistor was used to drop the voltage enough that it kept the coil
cooler and the points lasted longer.

However to ensure easy starting during engine cranking GM (and others)
used a bypass feed. This was for a simple reason. The ballast resistor
drops the line voltage from 12 volts to around 6-7 depending on the
charging system. However during cranking the starter (also a 6 volt
motor for many years) drops the battery voltage quite a bit. So now you
have maybe 8-9 volts while cranking, this gets cut in half by the
ballast resistor and you get poor engine starting due to the very low
voltage.

So if you do a 12 volt conversion you add a ballast resistor and a relay
that is triggered while cranking only. The relay will feed full voltage
around the ballast resistor to ensure the engine starts.

In your case the burned out resistor stopped all voltage.


This shows the original 6 volt ignition system.

http://www.auto-wiring-diagram.com/w...all-models.jpg

Full wiring diagram
http://i.ebayimg.com/00/s/MTYwMFgxMTQy/$%28KGrHqR,!lwE+F0cgfpDBQ!!VH3FSQ~~60_57.JPG



--
Steve W.

On Saturday, June 7, 2014 10:47:13 PM UTC-7, Ivan Vegvary wrote:
> Car has not been started for 9 years. Note: Converted to 12 volt battery and 12 volt ignition coil 15 years ago and run as daily driver until parked.
>
>
>
> Tried to fire it up and no spark. Messed around for hours, tried 3 different coils, etc. to no avail. Finally, upon bypassing the ballast resistor I got a healthy spark and car started immediately. (yes, with 9 year old gasoline)!
>
>
>
> The resistor (original, I believe) is installed in the negative side of the coil. It goes from the distributor ground to the negative terminal of the coil. The resistor measures approximately 2 ohms, has continuity and is extremely hot after cranking the engine for about 5-10 seconds.
>
>
>
> As I said, absolutely no spark with resistor in place, but healthy spark when bypassed.
>
>
>
> Question: Can't find any diagrams with resistor in the ground circuit of the coil. All diagrams show resistor wired in the hot circuit between the ignition switch and the positive side of the coil.
>
>
>
> Please note that this car was a daily driver nine years ago and nothing has been touched or re-wired since that time. Can't find listing for ballasts at Rockauto and other internet sites.
>
>
>
> Thanks you for your attention,
>
>
>
> Ivan Vegvary

Wow!! Thanks Steve W.

That's the clearest answer I found even after several hours searching on the web.

My coil is rated for 12 volts so I will simply skip the ballast resistor. BTW, if I were to install a new resistor (extremely inexpensive) I suspect that it should go on the positive (hot) side of the coil and NOT the way mine was wired.
Thanks you again,
Ivan Vegvary

Ivan Vegvary > wrote:
>Car has not been started for 9 years. Note: Converted to 12 volt battery a=
>nd 12 volt ignition coil 15 years ago and run as daily driver until parked.
>
>Tried to fire it up and no spark. Messed around for hours, tried 3 differe=
>nt coils, etc. to no avail. Finally, upon bypassing the ballast resistor I=
> got a healthy spark and car started immediately. (yes, with 9 year old gas=
>oline)!

On most cars, the ignition switch should be applying power directly to the
coil on the start setting, and through the ballast resistor on the run setting.

So, if the ballast resistor is open, the car will start but then as soon
as you let go of the key and it moves to the run position you will lose
spark and it will stall out.

So if you aren't getting spark on either run or start, but you DO get spark.
on both with it bypassed, you have something unrelated going on.

NOW... I _think_ your car doesn't have that bypass, that the ballast resistor
is always in circuit even during starting. You need to get the service manual
and make sure that is the case.

>The resistor (original, I believe) is installed in the negative side of the=
> coil. It goes from the distributor ground to the negative terminal of the=
> coil. The resistor measures approximately 2 ohms, has continuity and is e=
>xtremely hot after cranking the engine for about 5-10 seconds. =20

Sounds like your coil is bad.

The fact that it gets hot would indicate that it's good and the connectors
on it are good too.

>As I said, absolutely no spark with resistor in place, but healthy spark wh=
>en bypassed.
>
>Question: Can't find any diagrams with resistor in the ground circuit of t=
>he coil. All diagrams show resistor wired in the hot circuit between the i=
>gnition switch and the positive side of the coil.

Shouldn't really matter which side it's on, but you can rewire it to put it
in the hot side if you prefer. I'd probably do that unless it's very clear
that it was wired originally the other way.

>Please note that this car was a daily driver nine years ago and nothing has=
> been touched or re-wired since that time. Can't find listing for ballasts=
> at Rockauto and other internet sites.

I don't think the ballast is your problem, but you can probably use any other
6V ballast resistor off the generic rack.

I am assuming this car is as stock, that it hasn't been converted over to
a 12V system, right?
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."