need information on rebuilding Ford coils

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Craig E. Luton
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need information on rebuilding Ford coils

Post by Craig E. Luton » Mon May 29, 2023 12:09 am

I am working on installing new condensers I purchased from Langs. I am working on 4 screw brass top coils, 6 screw brass top coils and 4 screw copper top coils. Look at the attached diagram and you will see that I have recorded the ohms taken from point A to point B along with my readings recorded on the left. These were taken with my 40 year old multimeter. Are these readings within the normal range for these coils?
Look also at “Line 1” and where it terminates. According to the old coils I have, the line should terminate at C, not D. If I rewire the coil to the schematic will the coil work or will I ruin it?
I guess the last question I have is, are the metal top coils wired differently then the black top coils? I have to do 20+ metal top coils.
Thank you
Craig
img473.jpg


J1MGOLDEN
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Re: need information on rebuilding Ford coils

Post by J1MGOLDEN » Mon May 29, 2023 8:26 am

The Condenser and Primary Winding both have to be parallel to the points for the coil to function.

Those wires do not always connect to the same screws on top.

The best information on rebuilding coils is to let the experts do it, that would be Brent Mize and Ron Patterson!


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Re: need information on rebuilding Ford coils

Post by Moxie26 » Mon May 29, 2023 1:47 pm

No need to rewire the coil if you're just replacing condensers / capacitors.... Just remove old capacitor / condenser and connect wires of the new replacement unit that attached the former condenser/capacitor...... Many other steps are needed to properly calibrate physically and electrically.. the analog meter with the moveable needle gives more accurate readings.


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Re: need information on rebuilding Ford coils

Post by Dennis_Brown » Mon May 29, 2023 10:32 pm

I read recently in an older VF the wires to C and D were reversed on Ford coils from KW coils..
Look at VF volume 21 #2 , March Apri 1986 if you can.
A very good article there on coil rebuilding and on page 24 and at the bottom it mentions the wire reversal between the KW and Ford coils.
Hope this helps.


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Re: need information on rebuilding Ford coils

Post by Moxie26 » Tue May 30, 2023 8:16 am

Re- take readings with a analog meter, with a piece of paper slid in between the points on top , the reading between points A and B should be around 3300 ohms, to check condition of the secondary windings....... Just take your coils to a wire wheel to clean up the contacts on the box also to ensure accurate readings
Last edited by Moxie26 on Tue May 30, 2023 8:40 am, edited 1 time in total.


Moxie26
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Re: need information on rebuilding Ford coils

Post by Moxie26 » Tue May 30, 2023 8:25 am

Information previously on forum
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Luke
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Re: need information on rebuilding Ford coils

Post by Luke » Tue May 30, 2023 5:32 pm

Craig,

Robert and others have posted useful information and advice.

I have a couple of suggestions resulting from the data you presented:

(1) Coil 5 appears to give quite a different resistance than the others. Either you had a poor connection when measuring, or there may be something awry with that coil.

(2) You could 'calibrate' your meter with a 3k3 resistor (or 2k7 say). To some extent the more useful thing is that all but one of the coils are within a few % of each other, and so IMV are likely to be ok despite the apparently low reading, however measuring a known resistance should tell you if your meter is working properly, or not, and from that allow you to determine the accuracy of your readings.

FWIW I have just measured four coils here, they range between 2.62k to 3.38k across where you have measured yours and, if recall correctly, all work(ed) satisfactorily in the vehicle. Three are 'standard' coils, and one is plastic, I don't have any metal-tops so cannot comment on them. Measurements taken with a digital meter.

I believe it's been discussed before but as most of these coils will be 100 yrs old, give or take, it's useful to consider that the manufacturing of the era did not allow for precision. I would expect that unless you had coils from the same batch, wound by the same (careful) person on the same day with the same gauge of wire, you'd get quite a variation, particularly in the secondary winding.

For the sake of establishing a record for anyone that comes along, I may be able to measure a few more secondary windings later today. If so I'll report back with the results.

Luke.


Topic author
Craig E. Luton
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Re: need information on rebuilding Ford coils

Post by Craig E. Luton » Tue May 30, 2023 9:25 pm

Thank you everyone, I am going to borrow a digital meter to check my coils and will get back to this later. I did find the magazine Dennis mentioned and am going to do some reading. Another thing, being that my coils are either brass or cooper top coils my coils are probably KW coils and not Ford coils. Thank you, Craig


Scott_Conger
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Re: need information on rebuilding Ford coils

Post by Scott_Conger » Tue May 30, 2023 10:25 pm

... it's useful to consider that the manufacturing of the era did not allow for precision.
Luke, what is this statement predicated on?

Whether automatic or manually operated, coil winding machines of the era were perfectly capable of excellent consistency and repeatability. I doubt very seriously that the operators were allowed or even capable of picking/choosing when to stop or how many turns of wire were put on a core.

Across all spectrums of manufacturing, there were companies all over the world capable of creating devices made on machines to remarkable tolerances, fits and finishes. While we like to think we have the patent on precision in our "modern world" it is not like these folks were just winding lamp cords around broom handles and guessing when they were done.

Having been responsible for a sub-assembly area where stators were wound for synchronous motors, from experience, there is no doubt in my mind that small variabilities between operators occurs, and that is due to slight differences in tensioning and setup of the machine. Still, given the fixed resistance of the wire and the controlled number of turns, that natural variability is difficult to detect without statistical analysis of the motor's function as compared to the person who wound the stator. Similarly, when these coils were wound new, I would expect that random sampling of resistance measurements of new coils, would show very little meaningful difference in readings. I invite anyone knowledgeable of the machinery and processes to school me on where I am wrong, as I am drawing from present day experience and I was not working on the line at KW in 1913.

To reiterate: If coil winding was a sloppy, ad-hoc process, I certainly am prepared to be educated, but there is nothing in the history of manufacturing or machine technology which would lead me to that conclusion automatically.

Finally, there may indeed be a problem with coil #5, but in my experience it is not likely with the coil winding, but of a failure of the solder connection to the brass contacts which can be renewed by reflowing the joint and eliminating a cold/failed solder joint.
Scott Conger

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Re: need information on rebuilding Ford coils

Post by Luke » Wed May 31, 2023 2:10 am

Scott_Conger wrote:
Tue May 30, 2023 10:25 pm
... it's useful to consider that the manufacturing of the era did not allow for precision.
Luke, what is this statement predicated on?
Scott,

May I commend a series of articles by Trent Boggess and Ronald Patterson The Model T Ignition Coil which gives some information on coil manufacturing? There are some useful photographs showing part of the manufacturing process.

In addition to that the first few seconds of this video may interest: https://www.youtube.com/watch?v=IXkxl8dSXb4

While information suggests (see the article referenced above) that there were nominally 16600 turns on the secondary winding I've not come across specific detail on the winding process itself, nor on the supply of wire. If someone has that it'd be great to hear more, however at this stage I suggest that even if we accepted each coil had exactly that number of turns (and I have to say I have some doubt) they could well have been wound differently and thus have a different length of wire. By differently I include such factors as tension, stacking, former dimensions etc as all of these will affect the resultant resistance of the wound coil and in ~1920 I don't consider the precision was there (nor was it needed) to produce millions of exactly identical coils.

Also, as you'll know, even a small change in the manufacturing/supply of the wire itself could make quite a difference. Over the course of 20 years, and with the processes then available, I suggest that the resistance of say a representative mile of wire would vary somewhat.

Make of that what you will, I think the main point is that I think it unreasonable to expect every good coil to read precisely 3.3k on the secondary, and that a range might be expected. To that end I have provided a little empirical data here: https://www.mtfca.com/phpBB3/viewtopic.php?f=2&t=36796, if anyone wants to add to that I expect it'd be appreciated.

Luke.


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Re: need information on rebuilding Ford coils

Post by Scott_Conger » Wed May 31, 2023 9:53 am

I am aware of the article. Thank you.

I am not privy to the exact period procedure myself, either, but I ran a winding department manufacturing stators for miniature motors for about 18 months myself, and so am a little more than passingly acquainted with the equipment, processes, and sources of variability. Now, there is a difference between a procedure and a process in manufacturing, and while I will likely never read the (step by step) procedure that the factory used, I do know the general process, as we wound parts nearly the same as "T" coils, as well as windings that were far more complex. We did so while following a specific procedure so as to attain the product we were seeking. If for instance, we needed to turn (nominally) 16600 turns of "x" gauge wire, the counter kept pace and I would assume that the counter (or perhaps mechanical stops) did so in 1913, too. With respect to the operators winding coils for our cars, the job is a very delicate but not terribly technical job and it does not take very complex controls to assure a very precise job.

My suspicion is that after "x" turns of wire, the operator needed to continue winding until the lay of the wire resulted in the proper termination location, resulting in "x" turns plus/minus turns to end up at the right location/position for termination. Once tension was set on the wire, one could expect quite similar cores being wound until the spool ran out or the tension was otherwise altered. That would be the extent of measurable variability that I would expect from lot to lot. From a process control standpoint, using analog meters, I doubt that measurements were made on a sensitivity scale which would detect those over or under counts of winding and was simply "pass/fail". That would not indicate any lack of precision, but rather a practical application of a go/no-go test. It was either shorted or not; broken or not; over or under the nominal count of windings. For all I know, they used a Gauss-Meter (or Magnetometer?) to test the windings and not an Ohmmeter and cared not one whit for the actual resistance. There exists a chance that while we test coils with Ohmmeters (a valid test for resistance/continuity) we may not in fact be measuring for quality the same way the factory monitored for quality, and what we detect as variability or lack of precision, may in fact have been invisible to them - any one of our variable readings still falling within their range of "acceptable" on a Gauss-meter. In any event, whatever method was used, the engineer would want to use the simplest, quickest, most fool-proof method of testing possible that still provided a quality assessment of good vs bad.

The use of a Gauss-meter is simply thrown out as conjecture - for our testing, we always used an Ohmmeter, but we were not testing thousands of coils per day, and we needed to specifically know the exact resistance of the coil. FWIW.

I simply questioned the assertion that "precision" was not something the ancients were able to attain, and I still do.
Scott Conger

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Re: need information on rebuilding Ford coils

Post by Been Here Before » Wed May 31, 2023 10:48 am

So if coils have varied internal resistance, how can it be stated that to have a perfectly tuned ignition system all coils must be adjusted equally?

To have a perfect set of adjusted coils, the four coils have components including resistance and capacitance are equal.

Putting the hobby back another 60 years (c).


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Re: need information on rebuilding Ford coils

Post by Scott_Conger » Wed May 31, 2023 10:54 am

To have a perfect set of adjusted coils, the four coils have components including resistance and capacitance are equal.
uh...no.

they are set for identical output (ideally). Each coil may require more tension on the point, slightly greater or lesser point gap, etc. No two coils are identical in mechanical attributes, but can be made (essentially) identical in output by way of a number of possible adjustments.

Identical being defined either via amperage (old way), or TTF (new way)

You of course already know this. I won't get in your way any further in your attempt to confuse folks new to "T"s or simply to elicit replies.

Carry on.
Scott Conger

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Re: need information on rebuilding Ford coils

Post by Moxie26 » Wed May 31, 2023 11:06 am

If you have a bunch of coils to rebuild, it would make sense to group 4 like coils with somewhat equal secondary coil ohm readings to balance output. In the day manufacturing machinery could have been regulated to the same amount of secondary coil turns, I'm sure that those human operators could have overridden or shortened the amount of turns, thus affecting electrical values that we now are aware. Knowing Ford and his stinginess , and cut back on things , could have just as easily changed those machine settings.


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Re: need information on rebuilding Ford coils

Post by Been Here Before » Wed May 31, 2023 11:24 am

Sorry Folks.
"You of course already know this. I won't get in your way any further in your attempt to confuse folks new to "T"s or simply to elicit replies. "
Actually I know nothing. And I admit it. But by asking questions that other consider dumb, I may learn .

Oh, please define - "Identical being defined either via amperage (old way), or TTF (new way)"

Putting the hobby back another 60 years (c).


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Re: need information on rebuilding Ford coils

Post by Luke » Wed May 31, 2023 5:48 pm

Scott_Conger wrote:
Wed May 31, 2023 9:53 am
... I simply questioned the assertion that "precision" was not something the ancients were able to attain, and I still do.
If that's the only thing we disagree with I reckon we're doing ok ;) As it happens I suspect we simply have a different viewpoint, more than anything else.

While I'm in the mood to recommend literature, if you've not seen it before Simon Winchester's The Perfectionists: How Precision Engineers Created the Modern World is a worthwhile read 👍

Luke.


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Re: need information on rebuilding Ford coils

Post by Luke » Wed May 31, 2023 6:21 pm

Been Here Before wrote:
Wed May 31, 2023 11:24 am
... Oh, please define - "Identical being defined either via amperage (old way), or TTF (new way)" ...
George,

I think Mike Kossor has explained the two methodologies very well in various posts. I don't have links to those at present but I imagine a search would reveal them. Alternatively you could look at this thread in which these things are discussed in some detail: https://www.mtfca.com/phpBB3/viewtopic. ... 072#p66743

As I realise that the above is quite a lot of data, and has some complexity to it, a possibly useful 'executive view' might be that:

(a) the 'old way' measures coil average input current draw with an analogue meter, along with a view of output via a spark gap. You attempt to set coils [by adjusting the points] to be as close to a specified input current as possible while sparking well.

(b) the 'new way' precisely measures the peak current draw, and the time it take for a coil to 'fire' after power is applied to it. Coils are adjusted to achieve an identical time to fire (TTF) while sparking well.

Up until the 1940's the 'old way' was pretty much the only way in town. Once oscilloscopes became more readily available it was technically possible to introduce a better test, although I've no idea whether anyone ever did that. It was probably only in the 1970's that componentry actually allowed for more precision testing to be undertaken, but in reality it was the 2000's before this became more generally feasible.

As you may know Mike K has a complete built-up unit ready to go that you can buy (produced maybe 2010 give or take?), which will test coils the 'new way'. You could also build your own unit if you wanted (see the link above), or you can build/use one of the various iterations of testers based on the 'old way'.

With regard to the secondary coil resistance discussed here; that's, arguably, a separate matter. It may, or may not, have an affect on coil operation, and even if there is an affect it may not actually matter to the motor. At this point the discussion on that is somewhat academic, but it could lead to something further. To avoid messing with Craig's original thread/question any more I've started a new thread with that as a the focus.

Luke.


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Re: need information on rebuilding Ford coils

Post by Scott_Conger » Wed May 31, 2023 7:34 pm

Luke

it's kind of you to provide this in-depth info, but for George, it is the umpteenth time someone has related it to him. Asking this sort of question, or espousing the superiority of Buzz Boxes and waiting for inevitable replies has almost become a sport. I suppose there are worse ways to wile away the hours.

Have I pretty much nailed it, George? ;)
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Re: need information on rebuilding Ford coils

Post by Moxie26 » Wed May 31, 2023 8:23 pm

Essentially we're helping Craig,,..... not George


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Re: need information on rebuilding Ford coils

Post by Been Here Before » Thu Jun 01, 2023 11:41 am

Thank you Luke for providing additional information on the internal construction of the Ford trembler coil, or buzz coil or vibrator coil.

I am certain that Craig and others have a better understanding on the internal resistance and winding of the primaries and secondaries.

We all enjoy our car in our own way and we make certain that it performs with what tools we have on hand. Of course - some of us do get in trouble expressing our opinions.


Topic author
Craig E. Luton
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Re: need information on rebuilding Ford coils

Post by Craig E. Luton » Tue Jun 06, 2023 10:17 pm

Sorry I didn’t get back sooner but my computer was down. I borrowed my son-in-law’s digital ohm meter and got the following readings.
13.4
3.54
2.37
3.66
3.42
3.44
3.53 and 3.59 using the 20K scale. On all the other 12 coils I didn’t get any readings at all.
After reading what everyone said and studying written reports, I think I will install the new capacitors the same way they are installed in the coil now, clean up all the contacts and put in new points. Everything should work out that way.
Remember, these are all brass and copper top coils.
Thank you everyone that has replied to my post.
Craig

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