1934? Ballast Resistor - Troubleshooting

[dbtenner]

I previously wrote a post trying to understand why I had a problem with a weak spark on my 1934 Ford Roadster with a 8v battery.

After testing the battery (8.23v), I tested the input wire from the ignition switch to the ballast resistor and it read 7.7v. The output of the resistor was 3.2v down to the coil. It is my understanding that I should be getting 5.5v at the coil if I have a 6v battery.

I’ve determined that it is likely that my ballast resistor is bad. I’ve attached a photo of the one I have and would like to have it replaced but who sells it and should I have a specific resistor since I have a 8v battery?

Not sure if I have a 1934, 35, 36 ballast resistor. Is there a way I can visually tell?

Thanks.




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[JSeery]

Doesn't sound like a ballast resistor issue. If you are using an original type coil that is about the correct voltage to the coil. 5.5v would be way to much. If it is a tin can type coil, different story.

From the photo that looks like a circuit breaker next to the ballast resistor, so a total hodgepodge of parts. The CB was not used until around 1940. Need to figure out what you actually have. My first guess would be it is not a 34 engine. Also need to know what the coil is.

[bobH]

Not that this is any answer, however, there are old posts regarding the 'fix' for these old, original, resistors. And, I believe, based on age of the part, and likely corrosion at the ends, this is something we should all address with our old resistors. My recollection is to get the end of the resistor wire as clean as possible, and apply a small amount of acid-base solder, to make a positive connection. I can vouch that on my 34, and also on my 47, this small change seemed to make a reliable improvement. I've forgotten who originally posted on this, so I can't offer credit where credit is due. It might go back to 'rumbleseat' ???

[dbtenner]

Originally Posted by JSeery

Doesn't sound like a ballast resistor issue. If you are using an original type coil that is about the correct voltage to the coil. 5.5v would be way to much. If it is a tin can type coil, different story.

From the photo that looks like a circuit breaker next to the ballast resistor, so a total hodgepodge of parts. The CB was not used until around 1940. Need to figure out what you actually have. My first guess would be it is not a 34 engine. Also need to know what the coil is.

Thanks for the response. This is the coil type I have on the car. I believe the block is original to the frame.

Question, if I placed a 6v battery into the bay and checked the output lead to the coil is would also be 3v? I’m not familiar with ballast definition. IMG_6118.jpg


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[FlatheadTed]

GM has shown us the solder idea to ,The ballast resister you have is the original item ok for 34 through 35 they rarely give trouble but,The circuit braker next it is for the lights normal but looks like a later replacement , The 5.5 Volts to the coil would be OK if the test was done when it was cold , with 6 volt battery it should drop to around 3,1/2 to 4 Volts hot with a original coil . it should delver almost full battery voltage for starting cold ,With the 8Volt out put to 3,2 is to low ,the resister shouldn't be in the circuit with a can coil, if its a skip coil it would I think take the 7,2 ok, Going by the photo it might be the original coil I don't think it would take 7,2 volts (Skip is your friend ) ,clean all the wire connections ,Ing switch ect

[FlatheadTed]

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The out put from the resister should be around 6-7 volts with a 8 volt battery (hot )

[deuce_roadster]

I would put the distributor and coil on my Sun machine and eliminate anything there. Do you have someone in your area that could do that for you? I think all the resistors for the 6v systems were the same. Maybe someone just put a later combo with the breaker for the headlights in for the resistor. Is the breaker in use?
If you bypass the resistor and it still won't run your problem is either the wire between the resistor and the distributor or the distributor and its components.

[JSeery]

Originally Posted by FlatheadTed

The out put from the resister should be around 6-7 volts with a 8 volt battery (hot )

Are you sure, that doesn't sound correct at all. As far as I know the early Ford coils require an input in the 3 to 4 volt range. The battery used should not change what the coil is wanting to see.

[JSeery]

Originally Posted by FlatheadTed

The out put from the resister should be around 6-7 volts with a 8 volt battery (hot )

Don't think so.

[Bill OH]

I used rosin core solder on my ballast resistor and cleaned ALL connections on ignition switch (including the contacts within the switch) , ballast resistor and coil. At the ballast resistor clean the contact surfaces on the 4 nuts, run 2 of the nuts on the mounting posts followed by the the ballast resistor and the wires and then the 2 remaining nuts - tighten them up. Did this my 38 and made a big difference.

[JSeery]

Might want to take a look at this recent thread: https://www.fordbarn.com/forum/showthread.php?t=274307

[FlatheadTed]

,I agree Jerry ,With respect ,I did say that .[QUOTE with a 6 volt battery it should drop to around 3,1/2 to 4 Volts hot with a original coil,


I could be wrong but think If you are testing the voltage of the output side of the resister with a 8 volt battery and disconnected from the coil the resister would show a drop from 8 volt to around 6-7 volts (hot ) ,the resister in the 6 volt application drops it up to 2-1/2 volts ,I am not saying he should run it like that with the original coil .


=JSeery;1833695]Are you sure, that doesn't sound correct at all. As far as I know the early Ford coils require an input in the 3 to 4 volt range. The battery used should not change what the coil is wanting to see.[/QUOTE]

[JSeery]

Ya, think we may be talking two different things Ted (or the same thing accounting to how you look at it, ). Without the ballast being grounded the out side should be about the same as the input side, but not sure what that shows you.

An 8 volt battery in a 6v system can lead to a lot of issues like this, the system is just not set up for 8v batteries. But, then it depends on what the generator source is. If it is set up to charge an 8v battery, it will be putting out more than that running.

[FlatheadTed]

I agree ,ungrounded cold most likly = 8 v ,He said 3.5 ??,still need to ground it to get a reading ,

[Terry,OH]

Your resistor and circuit breaker is 39-40 style not 34, but should work. The 40 ignition resistor is the same as the 34. The 34 had a fuse block and resistor. It appears your resistor is installed up-side-down. The resistor puts out a lot of heat and since the heat rises it is going to the black mounting board material the mounting hardware and the electrical wires. Your ignition coil is also non Ford but a very old aftermarket replacement. Again it should work properly if still good, but probably not a good candidate for a rebuild if ever needed. I am posting this info FYI and not to criticize.

[Tinker]

Whats the point of a 8 volt battery. 6volts is fine. Dump the 8v.


3-4volts at the dizzy works well. Rebuild the original coil with skip, send the dizzy to bubba (do a search, no bad reviews), and buy a handful of condensers. Check your wiring to make sure it's solid or replace. Make sure it charges. we like to re-invent a system that has been well thought over. Lucky we have some rebuilders out there. Sometimes it's okay to put the round peg in the round hole.


If you want 6v at startup go with a 4 post 6v ford tractor solenoid. But less what your asking.
https://www.griggslawnandtractor.net...saAqA-EALw_wcB




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[Tinker]

Originally Posted by Terry,OH

circuit breaker is 39-40 style not 34, but should work.

Not sure if these work well but maybe they do. Easier then replacing fuses, but I've never blown one.. This only effects lights and accessorizes, independent to the coil. One wire off the resistor to coil.