testing for the existence of ballast resistor in my car
 

what's the simplest way to test for whether or not i've got a ballast resistor in the circuitry that runs from my ignition switch to my coil on my '41 ford? as i think i've finally found the reason that my E-Fire distributor is not working. i.e. it will apparently (buried very deep in the small print in the installation manual) not work at all with a ballast resistor, and i suspect my car has one.

and if i do have one, what's the best way to bypass it? hopefully one that doesn't involve laying upside down underneath the dash with both arms raised above my head for any more than a second or two. :)

Re: testing for the existence of ballast resistor in my car
 

On the 41 pickup its on the firewall under the rivers side dash. To bypass it simply place both wires on one stud. Tim

Re: testing for the existence of ballast resistor in my car
 

thanks. i saw it up there on my car too. but reaching it, let alone removing and attaching wires looks to be quite difficult as laying on the floor my arms are simply not long enough to even reach anything up there. could they have made it any more inaccessible? i'm thinking maybe it would be simpler to run a new wire from the ignition switch to the coil.

BTW, am i correct in thinking it's just a bit of ceramic inline with the ignition wire that when cold creates little resistance but heats up when 6v starts coursing through it and when it heats it becomes slightly more resistant and reduces the voltage to the coil thus putting less stress on it and the points. ...or something along those lines?

Re: testing for the existence of ballast resistor in my car
 

All you have to do is move either the red-black wire or the red wire connected to the resistor so both wires are attached to the same resistor post.

https://www.fordbarn.com/forum/attac...8&d=1772461274

https://www.fordbarn.com/forum/attac...9&d=1635130955

If you wish to check the resistance, disconnect the red wire from the coil. Now check the resistance from the ignition switch to the red wire end you disconnected, noting that the resistance will rise as it heats up.

Re: testing for the existence of ballast resistor in my car
 

ah!!! i think i see...

assuming the resistor is cold, when i turn on the ignition switch the resistance will be at it's lowest and steadily increase as time passes. can we assume that to make a second test, one would have to wait for it to cool down? and can i assume that it cools very quickly indeed, such that once the voltage is removed, restarting these cars BITD was not problematical?

Re: testing for the existence of ballast resistor in my car
 

Yes, that is how the resistor works.

Re: testing for the existence of ballast resistor in my car
 

As you mentioned, DON’T use the resistor with a Petronix module.

When starting with points, the resistance is very low and helps when starting. Once started, the resistor heats up increasing resistance and protecting the points from burning.

Re: testing for the existence of ballast resistor in my car
 

thanks guys, ...big help! should give me a couple of things to do. hopefully i can get my E-Fire distributor to work once i remove any ballast resistor that's in the circuit or failing that i can remove my traditional coil that's giving me fits, bypass the ballast
resistor and install my "modern" coil conversion kit and be done with the necessity to protect the points.

Re: testing for the existence of ballast resistor in my car
 

Points can be field adjusted and won’t leave you stranded

Re: testing for the existence of ballast resistor in my car
 

I have tested the output voltage of four original resistors and one aftermarket resistor. As they warmed, each dropped the voltage by only 0.2-0.4 volts. A few tenths of a volt seems to me to be negligible.

I think the theory of the higher voltage when cold to help starting is a myth. That technology did come into common use during the fifties, but then the resistor was actually by-passed during cranking. Not on our cars.

Re: testing for the existence of ballast resistor in my car
 

This is intentional. Part of the reason is that it can get very hot and you don't want to accidentally touch it.

Re: testing for the existence of ballast resistor in my car
 

understood...and they've succeeded beyond their wildest dreams AFAIC. :)

Re: testing for the existence of ballast resistor in my car
 

No myth and if not necessary to protect points why did the manufacturers spend the money for them?

Regarding, "not on our cars", the resistance is nil when cold. Now if you have trouble starting up your old Ford, the warming resistor can impede a quick start.

Re: testing for the existence of ballast resistor in my car
 

The ballast is to control the current draw of the old original type coil. Electricity works a lot faster than I do. A resistor will go to max heat the moment the circuit is closed. The old coils were a special design that couldn't reliably take a full current draw of a good 6-volt battery.

The breaker points are protected by the condenser. They are also constantly opening and closing the circuit to get the half wave pulsating DC current that allows the coil to function. This tends to drop the voltage and current a little bit as well but it's a negligible amount.

In the early 12-volt era, Chevy vehicles had a full 12-volt connection to the starter relay that boosted the ignition voltage for starting only. As soon as the engine was running, the circuit would revert back to the ballasted ignition switch wire.

Re: testing for the existence of ballast resistor in my car
 

Huey, if you were old and decrepit like many of us here, you’d know that your cel phone camera can be your eyes under your dashboard, saving you the upside down position on your back. Take a pic of the resistor’s connections to determine if the circuit goes through or bypasses the resistor.
To discover if it is connected without any of that, test the voltage at the ignition switch and compare that to the voltage at the coil while ignition is on. If your engine had stopped with points closed, with a resistor, you’ll get a reading of about 2 volts lower than at the ignition switch. Points open reading will be equal to the reading at the switch.

Re: testing for the existence of ballast resistor in my car
 

Don't forget Supereal's "Quick Start" circuit/modification...
https://www.fordbarn.com/forum/attac...9&d=1742506016

Re: testing for the existence of ballast resistor in my car
 

I believe that to be WRONG info. What I found in testing five different resistors is:
engine stopped (full current flowing continuously), voltage drop thru the resistor is right around 3.0 volt.

Re: testing for the existence of ballast resistor in my car
 

Exactly; unlike points there are no roadside fixes for a Pertronix; unless you keep a spare unit in the trunk.

Re: testing for the existence of ballast resistor in my car
 

My Pertronix quite on the road and I had a set of points and condenser with me to get me home. I did like the way it consistently ran until it stopped. If I go back to electronic, I'll bring another distributor all set set up with points and condenser.

Re: testing for the existence of ballast resistor in my car
 

I only run conventional points distributors in my old cars. NEVER have I even considered the possibility of carrying a spare distributor.

Re: testing for the existence of ballast resistor in my car
 

I’ve found that the most important spares to carry are a set of water pumps, a distributor, and a carburetor. During my touring years through most of these lower 48, they each were changed out at least once. (Your mileage may vary)

Re: testing for the existence of ballast resistor in my car
 

thanks again everyone!

did a little work on the ignition today and as it turns out i did have a ballast resistor in the traditional place and it was hooked up, and it was probably working as designed. i know it had continuity as the engine had been running and i had driven the car a few times. but...

as expected, it was a real PITA to work on. and much to my surprise, it had three wires connected to it. two on one stud and one on the other that ran to the coil. i think the third wire (conclusion based on fiddling with the wires on the studs) was to provide power to the turn signal stalk, which i'm assuming is or was an aftermarket product. and IT created another problem...

the problem being that instead of the straightforward and simple task of removing one wire and placing it on the other stud (as so graciously suggested by pistonbroke), i was burdened with the proposition of securing THREE wires on one stud, and therein lies the rub. as neither stud was long enough.

but nevertheless i tried...and tried...and tried. but try as i might the connectors got in the way of each other and once positioned on the stud i could never get more than about half a turn on the nut, (this was all performed, BTW, with one hand holding three recalcitrant connectors on the stud, while holding the nut in place and then turning it, and at all times attempting to keep all three wires from turning with the nut. and did i mention that i'm 74, i was lying upside down under the dash with the brake pedal hitting me in the head and working practically blind while my other hand was on the floorboard supporting the entire weight of my upper body which is considerable?) before it would pop off and fall down my neck and under the floor mat. extremely frustrating! so after about forty-five minutes of this nonsense i thought that maybe i could remove the ballast resistor altogether and gain maybe a 1/16th of an inch of stud length which might just be enough to get the nut on a full turn, get a socket wrench on it (13/32") so as to crush down the unused spaces between the connectors and secure it tightly. which i did. i'll have you know that i accurately predicted how miserable it would be without any knowledge of the actual reasons as to why it would be. ...i just knew. :)

so now i'm prepared to remove my traditional coil and install a "Modern" canister style coil using my "coil conversion kit" which has just been delivered as i write this! we'll see how that goes. and if THAT doesn't work i can always try to install my 6v positive ground E-Fire distributor again for the sixth time, now that i've discovered that the most likely reason it failed previously is that i had a ballast resistor in the circuit.

BTW i discovered my E-Fire installation error the other day, by contacting the company by email and asking specifically whether or not a ballast resistor should be used with their 6v positive ground distributor and they responded that it should definitely NOT be.

and so, being upset as to why that was not specifically stated in the their advertising, i thought maybe firing off a withering email barely hiding my contempt for their lack of thoroughness would be an appropriate response, but before sending an email i may later regret having sent (BTDT) i immediately re-read, completely this time, the installation instructions. and low and behold, i found buried in one of the Warning: sections verbiage reflecting that which was conveyed to me in their email response regarding use of a ballast resistor. "don't use a ballast resistor" it was written in the instructions. hmmm...

so on second thought i'll have to put most if not all of the blame on me for THAT one. eh? :)

Re: testing for the existence of ballast resistor in my car
 

Oh, to be 74 again! If you just use the stock ignition, you could have left all those wires in their place.

Ken

Re: testing for the existence of ballast resistor in my car
 

haha. funny you should say that, i had a composition professor say those exact words to me many times. i think it was a line from a joke that he had heard and found them amusing.

true enough about the resistor...i only removed it because i didn't know what state it was in and wanted to remove it as a variable in any subsequent tests. but more importantly, i recently found out that it MUST NOT be present for the 6v positive ground E-Fire electronic distributor to work properly. which i will probably now try to install again...sometime. :)

BTW, the '36 is probably my favorite old ford. i remember seeing one in an old 30's movie and remembered the dip in the front bumper, but hours and hours of research has never revealed anything. :(

Re: testing for the existence of ballast resistor in my car
 

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