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Restoring - General discussions that span across many different groups of years and models => Parts => Topic started by: markb0729 on March 29, 2017, 11:47:59 PM

Title: Yellow Top Coil
Post by: markb0729 on March 29, 2017, 11:47:59 PM
I've had my fair share of troubles with after market ignition coils so I've been keeping my eye out for an original Yellow Top Coil that's in very good condition and/or can be cleaned up and be presentable at car shows.  I'll pay more for one that is excellent condition but jeez, prices seem high to me.  Anyway, I came across this coil on eBay and it looks pretty good.  The coil appears to be an original yellow top coil but there is not any signs of an ink stamp.  Seller says that it works but I sent a message asking if they could get me the primary and secondary resistance readings.  What do you think, original?  Seems to be in visually good shape and the price hasn't been bid up...  yet.

Mark


Sellers Description:

FORD YELLOW TOP OR MUSTARD TOP COIL: this is a used coil for the classic Ford or Mercury, it is the yellow top. this came from an estate auction of an old Ford mechanic, it was in his desk drawer. I did have it tested and it has good spark. this coil has no ink stamp to show a part number. you classic Ford folks will have to sort that out to see if it will do the job for you. it has the dist. and bat. markings. I was told this coil was used on the Fords and Mustangs and Mercury Cougars 1965 1966 1967 1968 1969 1970 1971 1972. the buyer will pay 9.80 S&H.

Pictures:
Title: Re: Yellow Top Coil
Post by: 196667Bob on March 30, 2017, 05:02:01 AM
A couple of things to be aware of on your yellow top coil. First, they were first used by Ford in 1957. The earlier ones (57 to about 64) had a "bump" on them for indexing on the coil bracket (see attached picture). The later ones, from about 1965 on didn't have this bump.
As far as testing, what I normally do is after testing the primary and secondary resistances, is take my heat gun (or hair dryer if you don't have one), and bring it up to 150 degrees, which is about the operating temperature of a coil in a warmed up engine. If the resistances stay close to the "cold" coil resistances, you should be good. When the coils go bad, they usually break down under heat, and will give erratic readings.
In regard to the coils appearance, besides repainting the semi-gloss black, you can restore the yellow top if needed, using Rustoleum Satin Amber spray paint. It's very, very close to the original mustard top. Just do a careful taping job, and don't forget to tape off the Dist and Bat posts, and the inside of the "tower" where the coil wire goes.
As far as finding an original, you might check Mustangs, Etc. A couple years ago, they had a good supply of used ones that had tested (although not with the heat), at reasonable prices.
Hope this helps.

Bob
Title: Re: Yellow Top Coil
Post by: markb0729 on March 30, 2017, 11:57:03 AM
Bob, thanks for the info and advice.  Every little bit helps.  I sent off an email to Mustangs, Etc.  I'll see what they say.

Mark
Title: Re: Yellow Top Coil - Coil Resistology
Post by: 196667Bob on March 30, 2017, 02:21:50 PM
There was a question when I looked at this Post this morning that asked, "How do you test a coil ?". It has apparently, since been removed, but since I have prepared an answer, I will still Post it, since it is a valid question.
Typically, one might see a "Coil Test Procedure" something like I have attached (from the 1957 Ford and T-Bird Shop Manual). It notes what you are testing, and why, as well as testing at normal operating temperature (as I noted previously), but it doesn't tell you how to do it. It really is a rather simple procedure.
First, you need a multimeter (Volt/Ohmmeter) capable of reading 200 ohms, and 200,000 (200K) ohms. Also a heat gun (or hair dryer if you don't have a heat gun), and a way to measure the temperature of the coil (I use an infrared thermometer). An option to the heat gun and thermometer, is to start the car (after the "cold" testing), and bring the engine up to normal operating temperature. Then disconnect all wires from the coil, including the Distributor to Coil wire. Then do the test on the hot coil.
The test procedures are as follows :

1) For Coil Primary Resistance, set the meter to the 200 ohm scale.
2) Connect the Red lead to the "Bat" (+) terminal of the Coil, and the Black lead to the "Dist" (-) terminal.
3) Record your reading (for 1965-67 Mustangs, should ideally be 1.4 to 1.54 ohms.
4) For the Coil Secondary Resistance, set the meter to the 200K scale, leave the Black lead of the meter connected to the "Dist" terminal, and move the Red lead to the Coil tower (where the wire from the Distributor was), making sure that the lead makes contact with the connection at the bottom of the tower. This reading should be somewhere between 7600 and 8800 ohms (although I have seen some used "good coils" as high as 30,000 ohms). Record your results.
5) Repeat the same tests on the Coil at operating temperature and observe if it is a steady reading. Record your results again.
6) Compare the results. If the results of the "hot Coil" vary significantly or are much lower, then the coil is breaking down when hot, and should be replaced. All results are significantly higher or lower, then it should also probably be replaced. The values shown in books are typically for "new" coils, and some differences are to be expected with old or well used coils.

You can now be labeled a "Doctor of Coil Resistology".

Hope this has helped.

Bob
Title: Re: Yellow Top Coil
Post by: J_Speegle on March 30, 2017, 02:47:06 PM
Mark interesting that the one you show in your post lacks the markings between the post. Haven't really studied when that started or if it relates to the type of coil, date or other detail we have yet to discover but thought I would mention it. There are multiple applications and there are some that are slightly smaller than what was factory for our Mustangs. Bleive they were shorter by just a little
Title: Re: Yellow Top Coil
Post by: Brian Conway on March 30, 2017, 03:56:14 PM
Thanks Bob.  I posted the ' how to ' question and then pulled it.  Electrical issues and tests are a challenge for me.  For example; I tested a couple of coils and got 2.2 for the first test and 1.0 for the second test.  Of course nothing agrees with the ' test procedure '.  Brian
Title: Re: Yellow Top Coil - Coil Resistology
Post by: jwc66k on March 30, 2017, 04:03:15 PM
Also a heat gun (or hair dryer if you don't have a heat gun), and a way to measure the temperature of the coil (I use an infrared thermometer).
Or you could put the coil in the oven set to 150F for 15-20 minutes. Use a "hot" glove to handle.
Jim
Title: Re: Yellow Top Coil
Post by: J_Speegle on March 30, 2017, 04:23:02 PM
Do have some verbage related to the testing of the primary and secondary windings of the coil in preparation for an article on restoring coils. Will see if I can locate that and post
Title: Re: Yellow Top Coil
Post by: preaction on March 30, 2017, 04:39:50 PM
Mark, I have an extra can of the spray paint used to reproduce the yellow color of the coil email if you need one as Im not far away.
Title: Re: Yellow Top Coil
Post by: markb0729 on March 30, 2017, 10:29:47 PM
Great info guys, much appreciated!

preaction, I'll take you up on your offer for the yellow paint.  I'll send you an email. 

Mark
Title: Re: Yellow Top Coil
Post by: 196667Bob on March 30, 2017, 10:52:54 PM
Brian : A couple of things on your "Testing Procedure". First, a variance between readings of 1.0 and 2.2 is not common. Do you have the meter set on the lowest scale that would cover the typical Primary Resistance ? This is typically "200", but you may want to go up one scale, take a reading, then go back to the lowest scale. Are the batteries in the meter good ? Unlike Volt and Amp readings, Resistance readings rely on voltage from the batteries in order to measure ohms. Have you checked the accuracy of the meter ? This can be done by measuring the resistance of a known item; this would be like a resistor of known value.
Finally, values that I noted are printed values which are generally based on new, or like new coils.
That being said, I have read from many sources that "in general", values of Primary Resistance should be between 1.0 and 2.0 ohms; values for Secondary Resistance should "generally" be between 7500 and 9000 ohms (this value does vary between automobile manufacturers). Any readings beyond these "general" guidelines, would normally dictate that the coil be replaced.
One other thing to remember is that the Test Equipment that was used to come up with the printed values can vary, to some extent, from that being used on a current test.

Just a few things to think about before getting rid of that "bad coil".  One other item to consider; how does it perform when installed ?

Bob
Title: Re: Yellow Top Coil
Post by: preaction on March 31, 2017, 12:43:32 AM
This topic is uncovering many things, as I took a closer look at two spare coils to test testing them I found that both have info between the terminals one has 8A and the other has 7D would these be date codes ?
Title: Re: Yellow Top Coil
Post by: Bob Gaines on March 31, 2017, 11:01:40 AM
This topic is uncovering many things, as I took a closer look at two spare coils to test testing them I found that both have info between the terminals one has 8A and the other has 7D would these be date codes ?
those are not date codes. Date codes are on the ink stamp. Maybe a batch code for the mfg. it is one thing missing from the repros.
Title: Re: Yellow Top Coil
Post by: 196667Bob on March 31, 2017, 03:01:52 PM
Maybe a batch code for the mfg. it is one thing missing from the repros.

Bob : I wouldn't go so far as to say that these markings are "missing" from the Repros. While Mannel also notes in his book that these are not "date codes", he also notes that the meaning of these markings is "unknown". As I noted previously, these "yellow top" coils were used from 1957 (January), through the 70's, and available as Service Parts for many years after. I have these "yellow top" coils for my 57 Retractable and T-Bird, my 59 Retractable and Ranchero, my 62 T-Bird, my 66 Mustang and T-Bird, and my 67 Mustang, as well as a few spares. The majority of the ones I have exhibit no markings between the posts. While, unfortunately, I can't say which, if any, are original assembly line coils, I would find it unusual if the majority were not. I say this due to the fact that it is fairly uncommon for a coil to really "go bad", and thus that so many of mine have no markings there - of course it is a possibility. Maybe the ones with the markings were "assembly line only", and the ones without were Service Parts ? Or possibly just from different suppliers for the Plants ? In any case, I think it is something that requires further investigation/documentation before saying that all yellow top coils should have the marking between the posts.

Actually, I am more interested in something else that occurred with these "yellow top" coils. When the first 12 volt coil was first used in 1956, it was Part # B6A-12029-B, and was black, with a black top. In January of 1957, the coil received the "yellow top". In early 1965, the indexing "bump" on the coil was eliminated. In 1967, the coil became stamped "Autolite". Then, and I don't know what year for sure, the "yellow top" was eliminated, and, at least the Service Part, became black again. The Service Part remained like this until it was "Not Replaced" sometime after 1990 (again, I don't know when since my last OSI catalog is 1990), but do know that it is no longer available 'due to low demand". Throughout all of these changes, the Part # remained B6A-12029-B. The "something else" that I am curious about occurred sometime during the "yellow top" era ; the tower of the coil (where the wire from the distributor plugs in), became longer. When did this occur, and why ? Possibly a supplier variation ? Once again, not enough of a variation to warrant Ford changing Part Numbers", or even a suffix. As I have come across some of these, I am interested in finding out the details.

Bob

 
Title: Re: Yellow Top Coil
Post by: J_Speegle on March 31, 2017, 04:24:03 PM
................In 1967, the coil became stamped "Autolite".

That change took place in 1966 as discussed in a tread a couple of days ago

Check this thread out -  https://www.concoursmustang.com/forum/index.php?topic=2947.new#new (https://www.concoursmustang.com/forum/index.php?topic=2947.new#new)

For the period of cars we consider the classic years of Mustangs al of the originals I can recall had the small letter and number cast in the yellow portion of the coil
Title: Re: Yellow Top Coil
Post by: 196667Bob on March 31, 2017, 05:52:30 PM
Jeff : Thanks. I guess that I missed that. Are you talking about the part you quoted (change to Autolite), or the tower length ?

Thanks,

Bob
Title: Re: Yellow Top Coil
Post by: 196667Bob on March 31, 2017, 06:40:44 PM
Jeff : My "friend Search" found it - right below the subject of the 8 Track tapes - duh.
My info of 1967 came from Mannel's book, which is obviously then incorrect. Good thing the "Posting Police" (you) are out there checking for offenders.

Does anyone ever contact Mannel, or any other publishers (like Kevin Marti) when things like this are found incorrect in printed publication ? Just curious if there is any "failsafe" for those no having the benefits of a "Policeman".

Bob
Title: Re: Yellow Top Coil
Post by: J_Speegle on March 31, 2017, 09:06:08 PM
Does anyone ever contact Mannel, or any other publishers (like Kevin Marti) when things like this are found incorrect in printed publication ? Just curious if there is any "failsafe" for those no having the benefits of a "Policeman".

Sure they do - but with the printed word what are they (the author or publisher) to do other than make a note and maybe make a correction in a follow up printing if that is ever done.

Same thing happens with magazine articles - once it's in print it's gospel for some and outdated sometimes within months or a year.
Title: Re: Yellow Top Coil
Post by: 196667Bob on March 31, 2017, 09:29:39 PM
Jeff : I figured, and hoped that this was the case. I know that in the case of Mannel, he has issued a couple of "Addendums", most likely prompted by things just like this.

Just to make your other point clear ; am I correct then, that the general consensus is that all Factory (Assembly Line) coils from 1965-73, should have a number, a letter, or both between the two terminal posts ? Just want to make this clear for future questions.

Thanks,

Bob
Title: Re: Yellow Top Coil
Post by: Bob Gaines on April 01, 2017, 02:26:37 AM
Bob : I wouldn't go so far as to say that these markings are "missing" from the Repros. While Mannel also notes in his book that these are not "date codes", he also notes that the meaning of these markings is "unknown". As I noted previously, these "yellow top" coils were used from 1957 (January), through the 70's, and available as Service Parts for many years after. I have these "yellow top" coils for my 57 Retractable and T-Bird, my 59 Retractable and Ranchero, my 62 T-Bird, my 66 Mustang and T-Bird, and my 67 Mustang, as well as a few spares. The majority of the ones I have exhibit no markings between the posts. While, unfortunately, I can't say which, if any, are original assembly line coils, I would find it unusual if the majority were not. I say this due to the fact that it is fairly uncommon for a coil to really "go bad", and thus that so many of mine have no markings there - of course it is a possibility. Maybe the ones with the markings were "assembly line only", and the ones without were Service Parts ? Or possibly just from different suppliers for the Plants ? In any case, I think it is something that requires further investigation/documentation before saying that all yellow top coils should have the marking between the posts.

Actually, I am more interested in something else that occurred with these "yellow top" coils. When the first 12 volt coil was first used in 1956, it was Part # B6A-12029-B, and was black, with a black top. In January of 1957, the coil received the "yellow top". In early 1965, the indexing "bump" on the coil was eliminated. In 1967, the coil became stamped "Autolite". Then, and I don't know what year for sure, the "yellow top" was eliminated, and, at least the Service Part, became black again. The Service Part remained like this until it was "Not Replaced" sometime after 1990 (again, I don't know when since my last OSI catalog is 1990), but do know that it is no longer available 'due to low demand". Throughout all of these changes, the Part # remained B6A-12029-B. The "something else" that I am curious about occurred sometime during the "yellow top" era ; the tower of the coil (where the wire from the distributor plugs in), became longer. When did this occur, and why ? Possibly a supplier variation ? Once again, not enough of a variation to warrant Ford changing Part Numbers", or even a suffix. As I have come across some of these, I am interested in finding out the details.

Bob
It would be redundant for the markings to be a date code and also have a date code in the ink stamp placed on the coil. Besides compare a couple of different coil stamp date codes to the markings on the particular coil and they typically don't  match the stamp in any conventional sense. It is safe to conclude therefore that they are not date code markings cast into the coil . FYI the repros do not have those cast in markings. It is typical to find those cast in markings on 1965-1970 yellow top coils.
Title: Re: Yellow Top Coil
Post by: 196667Bob on April 01, 2017, 02:57:05 AM
Bob : I have never thought, nor meant to imply that the markings were date codes. My point was, the majority of yellow top coils that I have, and have come across, do not have any markings between the terminal posts. That being said, according to Jeff's response, the ones that don't have markings are not from the 1965-73 models - at least from the Factory for those years.
On my other question, do you know when and why the towers were lengthened ?

Thanks for your input.

Bob
Title: Re: Yellow Top Coil
Post by: CharlesTurner on April 01, 2017, 11:27:27 AM
I suggest the codes on the top of the coil may simply be a mold/cast number.
Title: Re: Yellow Top Coil
Post by: J_Speegle on April 01, 2017, 03:40:45 PM
Bob : I have never thought, nor meant to imply that the markings were date codes. My point was, the majority of yellow top coils that I have, and have come across, do not have any markings between the terminal posts. That being said, according to Jeff's response, the ones that don't have markings are not from the 1965-73 models - at least from the Factory for those years.

That is what I've found and seen.

As for the markings there was a point where some thought they might be date codes, since we often grab that as a first possibility, though it did not hold up once enough data was collected.  Surely it helped with tracking batches of coils.


On my other question, do you know when and why the towers were lengthened ?

"towers"  are you asking about the terminals or the bases of the terminals? Just trying to get with the same terminology   ::)
Title: Re: Yellow Top Coil
Post by: Brian Conway on April 01, 2017, 06:51:13 PM
Put the ' test ' to the coil currently on the 65.  Meter set at 200 ohms, red lead to BAT and the black lead to DIST.  Results are in: 2.0.   The secondary test yielded an inconclusive 1.0 ?  This coil has a raised mold or date stamp: 5D.  So correct in either case for my car ?  Brian
Title: Re: Yellow Top Coil
Post by: midlife on April 01, 2017, 08:27:29 PM
Many DVM's register 1.0 when resistance is higher than that setting can handle.  Re-set your meter to 2 megaohms or 200 kilo-ohms and try again.
Title: Re: Yellow Top Coil
Post by: 67gta289 on April 01, 2017, 08:48:37 PM
Or get an auto ranging model ;)
Title: Re: Yellow Top Coil
Post by: markb0729 on April 02, 2017, 01:39:10 AM
Brian, Remove the wires from at least one of the terminals on the coil and retake the measurement.  You could be measuring resistance somewhere else in the circuit.
Title: Re: Yellow Top Coil
Post by: 196667Bob on April 02, 2017, 12:03:34 PM
+1 on midlife and 67gta289's Replies. To avoid any confusion for future readers of my "Test Procedure", I have modified my original Post to include setting the meter to the 200K scale when measuring Secondary Resistance. Of course if you have an "auto-ranging meter, this won't apply.


"towers"  are you asking about the terminals or the bases of the terminals? Just trying to get with the same terminology   ::)

Jeff, what I refer to as "the tower", is the "snout" on the coil into which the "spark plug type" wire (typically referred to as the "Coil Wire")  from the Distributor is inserted.

In trying to find information on the Coil markings and the length of the "tower", I ran across some information that most likely was not enough to justify the addition of the "markings", much less a change in Part Number (the B6A-12029-B Part number was used until the Coil was finally "Not Replaced"), but nevertheless, interesting. The 12 Volt Ford Coils from 1956 through 1966, all show the Spec for Secondary Resistance as "8000-8800 ohms". The Spec for coils from 1967 through at least 1971 (the last Ford Shop Manual that I have when points were still used), shows Secondary Resistance of "7600-8800 ohms". Just an interesting "tidbit" of information.

Bob