The Stovebolt Site Forums The Shop Area The Electrical Bay Ballast resistor placement

I’m rewiring my 1963 C10. Things are going well.
The original resistor wire will be replaced by a ballast resistor. That will make changing over to an HEI distributor later a lot easier (if I ever change).

Two questions.
Does the ohm rating of the ballast resistor matter? Mine measures 1.6 ohms. The original resistor wire measures 2.5 ohms.

Is it ok to install the ballast resistor inside the cab? I would rather have it hidden under the dash than visible in the engine bay.

I have shown this before. I put 2 ceramic resistors in an electrical conduit box to capture their heat for the defrosters. They are wired so I get 2 speeds at the fan.

I've seen ballast resistors clamped to the side of the coil. I'm not recommending that but it's a possibility. My choice is the firewall.

Years ago I would not have understood the wiring. I’ve learned some things and it now makes perfect sense. I recently helped a friend install a new heater fan switch that had settings for fan speeds of OFF - LOW - HIGH . The back side of the switch had a coil of wire secured on a post of steel at each end. There was another post of steel merely laying on the coil in the middle of the coil to make contact. The speed was determined by which contact point was used to conduct the current through the resistor wire. ( I realize that I’m explaining what you already know.) The guy I was helping had no idea how it worked or how to test if the brand new switch had gone bad (because it wouldn’t work after installation). We got it working!

Ignition resistors develop a considerable amount of heat- - - - -That's why the wire is mounted in a ceramic housing. It needs to be mounted somewhere there's a constant flow of air across it- - - -under the hood and in the airflow of the fan if possible. Under the dash sounds like a possible source of odors, or maybe a fire hazard.
Jerry

Chevy designed them to be mounted on the firewall. Vertically, drivers side above and approx inline with manifold. That's where it belongs. It won't heat up more than it's supposed to. Firewall is a heat sink.

Last night while perusing EBay, I found some NOS Delco Remy ballast resistors in the form of a wire. Not the ceramic type I’m used to seeing.

Anyone know what application used those? Judging by the look of the packaging, I’d guess them as 1960s vintage.

Yep- - - - -mid 60's to mid 70's before the HEI came along. It's a piece of nickel/chrome wire about 6 feet long with heat-resistant insulation (woven fiberglass, I think) that doubles back on itself inside the wire harness for a couple of feet and goes from the ignition switch to the coil. Vehicles that run that wire have a second ignition switch terminal (IGN 2) that is only used during starting, that bypasses the resistance wire.
Jerry

This is where I mounted it on my 53. No issues yet.

Yes, that kind of wrapped wire is what I originally had in my 1965 and 1963 trucks. There is a woven sleeve like Jerry said. A normal 14ga wire from the key switch goes to the firewall disconnect. Then the resistor wire goes from the disconnect to the starter R terminal. A 14ga wire (green I think) goes from the R terminal to the coil. The Violet wire from the key switch supplies 12V to the S terminal during cranking. Then the resistor wire circuit takes over when switch is on RUN.

My truck (1951 truck 12v conversion) has an additional wire that bypasses the resistor during cranking. Would that be effectively the same thing as additional terminal on the switch?

Did these work OK? It would be slightly less noticeable that the ceramic one on the firewall.

Correct me if I’m wrong. While cranking the starter, the wire to the solenoid supplies 12V. The R terminal also sees 12V during cranking because of an internal connection within the starter from the solenoid to the R terminal. Once the key switch goes to RUN, the S terminal goes to 0 volts and the resistor wire circuit supplies the only current to the R terminal.

I think you are correct in the case of a key start. Same idea with my foot start, but the full 12v only comes into play when your foot is on the button.

I'm pretty sure the 12V foot start trucks had a second ignition switch terminal (IGN 2) that was included in the bypass circuit to keep voltage from being applied to the coil during cranking by the bypass terminal on the foot switch if the ignition switch was turned off. The "I" terminal on the key start solenoid serves the same purpose as the small bypass terminal on the foot start switches- - - -supplying battery voltage to the coil during cranking.
Jerry

I don't want to cause any confusion & its not really material but when the starter is cranking & the resister is bypassed you have FULL battery voltage to the coil but you still don't have 12 volts, as the heavy load of the starter drops the battery voltage to about 9-10 volts.

George

That's the whole purpose of the bypass- - - -to prevent the resistor from reducing the voltage available to the coil further during cranking.
Jerry

Agree, that was a better way to say it.

Correct me if I’m wrong. While cranking the starter, the wire to the solenoid supplies 12V. The R terminal also sees 12V during cranking because of an internal connection within the starter from the solenoid to the R terminal. Once the key switch goes to RUN, the S terminal goes to 0 volts and the resistor wire circuit supplies the only current to the R terminal.

Not quite Lugnutz. Once the key switch goes to run, R terminal is dead and the resistance wire takes over. S is dead also as you say.

JW: Keep the ballast resistor. I always change from resistance wire to ballast.

I meant that you could measure voltage at the R terminal. I did not mean that the R terminal post was supplying voltage. The voltage at the R terminal post is actually supplied through the ignition circuit wire coming from the key switch. Since those wires are directly connected to the R terminal, a voltage could be measured from the R terminal to any common ground.

We ahve all gone way off path from your question. It has been answered. No need to discuss measuring. The R terminal and resistance wire is wired at least two ways depending on year and probably whether Chevy or GMC. But we/you are using these methods on trucks that were 6V, so a person can choose several bypass methods when converting. The methods and the wiring changed several times and folks mix and match and tricky ideas. In a discussion like this the methods can get mixed up. None of it is difficult.
My quick list
1. Ballast with foot switch side terminal
2. Ballast with electical relay/solenoid (A and B)
3. Resistive wire method A. (R terminal)
4. Resistive wire method B. (R terminal)
5. Separate SS581 relay trick
6. Various ignition switches, including push button, Ign 2
HEI, pertronix and all that jazz

The ballast resistor has moved around at least 3 times. I’m finally happy with the location and it keeps the wiring clean and tidy. The wire loom has not been installed yet.
The ballast resistor now resides just in front of the coil of my 230 inline 6.
The drawing shows how it’s layer out because following the wires in a photo would be difficult.
Yes, the distributor has a Pertronix unit inside which explains the extra wire on the + side of the coil.

1. I don't think your wiring is per Pertronix instructions.
2. You have a hot ballast resistor next to a hot coil and a hot motor. If it's OK with you it's OK with me, but GM mounted it on the left firewall as I spelled out.

This is how they want is supposedly. I think you could add the dotted part. See what you think. THINGS CHANGE DEPENDING ON WHAT VERSION OF PERTRONIX YOU HAVE, SO BE CAREFULL WITH COIL OHMAGE.

Why are you using a ballast resistor with a Petronix ignition?

That is what I was thinking. I searched and searched and searched. Pertronix is very Flaky about that. Most of their instructions say they recommend NOT using the resistor or resistance wire IF you use their coil or a "proper" ohm coil. The original unit and the II and III have different instructions and requirements. Even though they say not to use a Resistor, they still show you how to use one if you want to or the motor/era had one with xx ohms. I saw three different ohm values for coil mentioned by Pertronix.
This is why I cautioned Lugnutz to be carefull with ohms. I decided not to say "you don't need a resistor because a resistor is to protect points and you don't have points".....but pertronix cautions the unit can burn out if too little or too large coil resistance....so I'm non-commital for fear of wrong info, not knowing what unit and what coil ohmage he used with his 12V conversion.........I am now out of breath.

OK, AFTER TWO SWIGS:

If you know what coil ohmage you have, know the model Pertronix, read that instruction, know what the resistor ohm is, you can do the math to see of you leave the friggin resistor in or not. What I would do for sure is find out what coil is need from pertronix and eliminate the resistor.... BUT after all that they say their coil is INTERNALLY RESISTED So if I'm reading all their many different pages correctly and sorted it, they recommend NOT using a ballast or wire but buy their coil, which is resisted and sounds like a 1.5 OHMer. I'm amped up about a device I will never use, but I have pills for that.

This is not anything against Lugnutz.....it's a general evaluation for anybody.

My truck originally came with a resistor wire instead of a ballast resistor. I think my resistor wire is in questionable condition, so I decided to replace it with a ballast resistor. The ballast resistor functions exactly the same as a resistor wire.

I consulted the PERTRONIX package insert before deciding to do anything. You can see for yourself what it says on #3.

In addition to the above, I have been driving the truck for approximately three years with the RESISTOR WIRE and the PERTRONIX unit installed inside the distributor. It runs great, starts without hesitation, and is the best engine I have. I would gladly have another engine just like it.

So you have the old version.. requiring a min of 1.5 Ohms. If that is what you have, good.

According to fig 3 you have it wired wrong, as i said.

If I remember correctly that older version was what gave them a bad quality record. It also burns out if ignition left on. Later versions were better.

Here is another bunch of conflicting verbage from Vintage Performance.com about the "Standard Pertronix"...(older version) FWIW

"The standard Ignitor is recommended for basically stock or mildly modified engines. Teamed up with a PerTronix 40,000 V Flame-Thrower Coil, the Ignitor will provide more than enough spark energy for almost all applications. We have customers running in the 11s and 12s in the quarter mile with this combination. The Ignitor can be used with OEM type coils.
Caution - some aftermarket coils have lower primary resistance than an OEM or the PerTronix Coil. Using one of these could damage the Ignitor. Rule of thumb - for 8 cylinder applications the primary resistance in the coil circuit must be 1.5 ohms minimum. For normal performance 6 cylinder and 4 cylinder applications the primary resistance should be 3 ohms minimum. Primary resistance is measured across the negative and positive terminals of the coil with all other wires removed. If you have a ballast resistor in series with the coil, its resistance is added to the coil resistance.
Many older vehicles have resistor wires feeding power to the coil when the engine is running. The resistor wires are bypassed when the engine is being started and full battery voltage is fed to the coil to facilitate start-up. These wires were intended to reduce the voltage to the coil once the engine was running in order to extend the life of points. Most of the time an Ignitor will work well with the resistor wire left in the circuit. However, in some cases the resistor wire, or its connections, may have deteriorated over time resulting in an excessive voltage drop at the coil. This could adversely affect Ignitor performance, especially at higher RPM, resulting in misfires. The resistor wire may be bypassed and a full 12 volts can be fed to the coil as long as the coil resistance requirements mentioned above are met."

Many people are having very good luck with Pertronix. Some of us engineers and enthusiasts have it in our heads that the resistor protects the points. So no points, no resistor needed. BUT Pertronix circuitry needs a certain resistance to remain dependable. With or without a ballast resistor, the ohmage math must result in what a version needs.

Also: Notice my RED in above "info".

My coil has 1.9 ohms and the ballast resistor has 1.0 ohms. Total = 2.9 ohms.

I have it wired to feed 12 V during start up and then current through the ballast resistor when the engine is running. Study the diagram carefully. Voltage to the coil is fed from the R terminal on the starter and bypasses the ballast resistor.

I did study it carefully. It is not wired per the Pertronix document you posted. I also offered a way to use R and Pertonix diagram at the same time. I am not an expert on Pertronix. I just "study" what they publish.
Trying to help. You can wire it anyway you want and we will still be friends.
I know you know what you are doing, no shade from me.

Lest anyone think I’m stubborn and won’t listen.
I now understand what Bartamos is explaining. My Pertronix red wire is designed to get a full 12V at all times WHEN THE ENGINE IS RUNNING, (not just during cranking).
The way I currently have it hooked up, the Pertronix red wire only gets a full 12V during cranking. The RUN ignition wire feeds to the ballast resistor properly, but I should have the Pertronix red wire connected to the ignition wire BEFORE the ballast resistor.

This is indeed a technical point I missed all because I’ve been running the same Pertronix unit for several years without issues and the Pertronix red wire was always connected to the + post of the coil. Since the original resistor wire went from the firewall to the R terminal on the starter, the setup I’ve been using for years only gave the Pertronix red wire the voltage AFTER resistor wire.

Understood, you are not being stubborn. You have the right to do things the way you see best after you recieve all the BS from us.

Here are the original questions:

"Two questions.
Does the ohm rating of the ballast resistor matter? Mine measures 1.6 ohms. The original resistor wire measures 2.5 ohms. ANSWERED BY OPINIONS AND PERTRONIX DATA

Is it ok to install the ballast resistor inside the cab? I would rather have it hidden under the dash than visible in the engine bay." ANSWERED BY OPINIONS ABOUT HEAT AND GM DESIGN LOCATION

Noted possible conflict with your wiring diagram vs Pertonix diagram