dfolse62

In the wiring diagram in the assembly manual it shows two wires going to one end of the resistor. One from the starter (what is the purpose of this wire?) and one to the +coil. How many volts should these show? The two wires on the other end, one goes to the ignition switch and one goes to the wiper motor. How many volts should be shown here? I seem to be getting a weak spark from the coil. Put in new coil and resistor today. Maybe a little better, I just want to be sure the wires are hooked up right.

Also, how hot should the resistor be. Mine is as hot as an iron, it doesn't take long to feel it. hot!

tach drive 61

yes hot do not dare touch that baby, I put a aftermarket original style coil in my 61 last year standard brand , well standard junk ! all kinds of trouble after that . put the 49 year old coil back in car and it runs perfect ! I checked my ballist resister for continuity with a simple ohm meter cleaned up the connections well , be carefull when doing it ,

Frankie the Fink

The attachment is a pretty typical GM starter/running circuit setup....the wiper motor should be attached to the 12V side IIRC. And, yes...the ballast resistor gets quite warm...

The thumbnail contains a graphic that shows the ballast resistor (red circle) and the wires that attach to it.

Its pretty hard to eyeball a spark and determine how weak it is unless its VERY weak. Best way is to look at a plug or two and make sure you are getting a nice even burn...no sooty deposits or unburnt gas on the tips...

dfolse62

If one end shows 12 volts, what should the other show? Will this fluctuate? What is the down side of skipping the resistor as some have done? One other thing. If one side is lower voltage to the coil, what is the purpose of the wire to the solenoid? Does this give 12 volts when cranking?

Frankie the Fink

Do NOT bypass the ballast resistor unless you have changed out your points with Pertronix or something similar and changed to a low-ohm, aftermarket ignition coil.
You will overheat your coil and tax other components.

Yes...the car cranks on 12V (e.g. solenoid connection) but takes less to run...some will say you should see 6V - 7.5V on the other end of the resistor but it may fluctuate somewhat....the 'ballast' nature of the resistor is a whole electronics lesson in itself and provides an "anchor" for the ignition coil saturation and drain process. It is a "current limiter" first and foremost and the voltage drop is merely a function of that primary purpose.

Don't dick with this unless you are upgrading the ignition system....its engineered the way it is for a reason!

62Jeff

The 62 resistor should be a 0.3 Ohm resistor. Did you get one that matches that specification?
http://forums.corvetteforum.com/1567167076-post6.html


The resistor lowers the current going to the points while the car is running, the pink wire to the starter bypasses the resitor while cranking.

Unless I've got my head up my rear today.

By definition, a resistor will heat up as it does it's job of providing resistance to a circuit, lowering the voltage that makes it across the resistor coil. The dimmer feature of your headlight switch similarly has a resistor coil on it and also heats up if your headlight switch is set to anything other than the full-bright setting for the dash board lights.

It's not uncommon for brand new ballast resistors, or headlight switches, to smoke a little and smell the first few times they are used as manufacturing junk heats up and burns off.

jimh_1962

What is IIRC is that like NCRS? If I recall correctly it is a ancronym for something not sure for what.

Frankie the Fink

Cute James...

toddalin

The voltage on the "downside" of the resistor will vary depending on if the points are open or closed. If the points are open, you should read the full voltage regardless of if the resistor is in the line or not. However, when the points close and you pull current through the circuit and the voltage will drop.

JohnZ

You might want to read this - it explains the ignition system operation, including the function of the ballast resistor:

http://www.lbfun.com/warehouse/tech_...tionBasics.pdf

dfolse62

Thanks everybody. I do think I understand now. I was just chasing a crap condition. Thanks for the link John. I think my problem is gunked up plugs from cranking and not driving during the past three months. Pulled one and it was wet and covered in black soot. Putting in another set in about an hour. There is a show in town tomorrow for charity that I am going to. Either to show or just go (in the 62 of course). Or maybe the 73, uh maybe the 81 anyway, I'm going. Darrel

69427

A couple technical disagreements here. The ballast resistor does not change the coil voltage. The coil operates under nominal 12 volts during run mode, and less during cranking. There is no system voltage change caused by the ballast resistor. The resistor limits the peak current into the primary winding of the coil. That is the function of a resistor. It does not regulate the voltage that the coil sees. An oscilloscope will verify these statements.
The starter shunt circuit is there to bandaid situations where the battery voltage is low due to cold temperatures and high starter currents due to thick oil, common in northern parts of the country. The shunt wiring (around the ballast resistor) helps to restore some of the needed coil primary current to fire the plugs. The coil voltage during this shunt phase is lower than the coil voltage during the run mode. The coil voltage during cranking is usually 8-11 volts, while in the run mode the alternator is impressing 13-14 volts into the ignition system.
The vacuum advance unit is there to vary the timing due to load. We agree there. However, I disagree with the statement that the VA is used to modify the timing due to A/F ratio. A/F ratio and load are two entirely different issues. The VA has no way of knowing what the A/F ratio is, or if it's varying, and only varies the timing due to cylinder pressure, indirectly measured using manifold pressure/vacuum.

dfolse62

Well, without getting too deep, I pretty much understand the basics of this. Problem is, something else is wrong. Probably fuel. It acts like sometime its not getting gas, but also flooding! Cranked it up running about 1800 rpm to warm up and clean up and it just dies. Pumping doesn't help. Still has voltage to the coil. Went for a test drive, going about 40, motor dies, I pump gas and it starts back up on its on. Coming in driveway, totally dies. I coast to a stop,crank it and it runs.

Stock 327, Carter afb, manual fuel pump. I looked at the jets last week and they seemed to be clean. If I loosen the line between the filter and carb, gas squirts out under pressure so I suppose the fuel pump is working. What gives, is it crap in the needles flooding the car or what. By the way, a couple of months ago I put in a new sender and pick up. I haven't driven it hardly any since then. What steps do I need to take to trouble shoot? Carb, fuel pump, filter. Thanks

toddalin

You are incorrect. The article is correct in that the ballast resistor does lower the voltage at the coil.

As I noted, when there is no load on the resistor (points are open), the full voltage comes out of the ballast resistor. But when you load it, the current can't keep up with the demand of the low resistance through the primary windings and the voltage "sags." The resistor's impediance is selected with this "sag" in mind, which is why it is important that the coil and resistor be matched.

RoadKing96

So now I'm confused. Nothing new there....

Seems I recall reading where if you have replaced the mechanical points with electronic setup, you no longer need the ballast resistor. I thought this was so, because a function of the ballast resistor was to drop current to the actual points, so as not to burn em up as quick.

Now I reading that I'm possibly, or actually, doing damage to my coil and maybe other components? Can someone please clarify, because the car sure seems to have been running a smidge better since taking ballast resistor out of the circuit.

Thanks in Advance,
RK

toddalin

You take it out if you have an electronic ignition module because the "trigger" is no longer carring the heavy current load. The ignition module pulls that directly off the battery, at least in the case of my Mallory. The coil should be matched to the system.

I retained Accel points and the point mearly act as a switch to trigger the Mallory box. Other systems work in similar ways though the "trigger" may be completely different. So in my case, the Mallory wants the full voltage as a trigger signal, and the ballast resistor is bypassed, but no harm is done because there is no real current going through this wire or the points. The points carry no current so they don't pit or go out of adjustment.

If you run points and coil without some sort of ignition module, you will get a hotter spark without the ballast resistor and yes the car runs great. But you will burn out the points in short order and can damage the coil from excessive heat.

When you start the car, you need all you can give it in every way, so the resistor is bypassed. But this only lasts for a few seconds at a time, and the parts are typically cold, so the additional heat and wear on the points and coil are considered as acceptable.

RoadKing96

It's a drop in electronic replacement that simply replaces the original points. There are no additional boxes. Everything fit nicely inside the distributor cap where the original points once lived.

I believe it only came with instructions on how to install, and I don't remember any mention about anything else, such as coil matching, ballast resistor, etc.... That's why I'm sort of lost on the ballast resistor question. I installed this dern thing about 15 years ago, but just recently took ballast resistor out of the circuit, and car seems to run better. So I guess I need to dig through my old records to see if I can re-find those instructions, and see if there might be some hint at other stuff that I might have missed.

What's worst case damage I might do? I damage the coil from excessive heat? If so, maybe I'll pick up a cheapie at NAPA tomorrow.

Thanks much,
RK

Frankie the Fink

The OP would have been better off describing the problem he is trying to fix (which may or may not be electrical) rather than getting all the other posters marching down the road with ballast resistor explanations...

I don't believe you will get a 'hotter' spark bypassing the ballast resistor on a points system either. Voltage is potential energy...nothing more...when it builds up enough potential energy to jump a distance it will. If your points are set at .017 and plugs are at .035 guess what happens when there is enough voltage built up to fire across the gap ? It fires. Doesn't matter if its takes 25,000V or 45,000 volts. Reserve voltage is a benefit if you have higher compression, increased gaps, fouling plugs, etc..

SOME, repeat SOME, points replacements will run with the ballast resistor in OR out. I ran my Pertronix Ignitor II both ways for many months and there is some benefit to the higher voltage with the ballast out simply because the solid state circuitry is running at a more optimal voltage....with the Ignitor III you MUST have a full 12V for it to operate, meaning NO ballast resistor.

dfolse62

You are right! I'll do a new post in a little while. My first thought was electrical, so I just wanted to know what I was looking for. See you on the the new thread. Darrel

69427

Sorry, partner, but you're incorrect. The ballast is there to limit current. Period. It is not a voltage regulator. Please show me any law of physics or enginering that says a resistor is a voltage regulator. It is a (crude) current limiter.
I spent 24 years at a major OEM designing ignition modules and ECMs/PCMs. I can back up my claims regarding how the various parts of an ignition system works. And in any detail you wish.