MTFCA Forum

I wouldnt expect a capacitor to ever fail in a rebuilt coil.
A well tuned coil will have minimum point wear, but will wear. They are sparking points.
Like the old days with point distributors, points needed attention.
I think we have forgotten due to the maintenance free nature of our modern vehicle ignition systems.
As is the nature of most things, they go bad slowly & we dont realize till their poor function is finally real obvious.
An annual check on our coil tune couldnt hurt, especially if you have access to an ECCT unit.

Testing and adjusting as needed will prevent problems with the points and timer. Every year or every 2500 -3000 miles should be adequate, unless points are changed or dressed or performance indicates otherwise.

Did Ford have any kind of service time schedule for a T’s coils? Or did car dealerships have service schedules other than service bulletins and schedules?

Steve,

I promise that I read many of your posts, but I'm guessing here that you used one of Mike's testers?

A couple of comments; when you say (of the '2011' coils) "I think they were readjusted last year" do you mean that Ron re-adjusted them, or you did? I cast no aspersions here, it's just that if someone else's equipment was used to set the coils they may well measure differently on your testing equipment. I'd not expect this variation so much in electronic testers however.

Given you seem to use your vehicles quite a bit I'm surprised that any coils restored 12 years ago or more are still testing well. In my view, if you've got a decent tester then I'd have thought checking the coils at least once a year (or more regularly if you do a lot of miles) is not a difficult chore and would be good practice. It'd also maximise the return on your investment in the tester

Otherwise, having just quickly visited Mike's site, I see the three indicators for the capacitor test. I imagine Mike has set a criteria for relating measured capacitance to simple 'health', but I have an idea he has additional software that may give more detail? I mention this because, to my mind, the level at which one declares a capacitor 'good' or 'excellent' is somewhat arbitrary (particularly if you don't know anything about the installed capacitor) however if you knew what the actual value was it could be useful to record over time for each coil in order to observe if there's any deterioration.

Luke.

So, what is the manufacturer's tolerance (not values, but tolerance) for the two typical caps used in rebuilds 11 years ago? I'm sure that data exists, but am not personally aware of what it is. FORD min/max was their spec .4-.45 uF. Some modern caps come with quite a wide tolerance, not that I know what the hobby's caps come with other than they come as .47 uF +/- some value which is already out of spec per FORD documentation. GADS!

I'd like to meet the guy who has actually torn down a functioning coil to replace a cap that still checks checks "good" but has drifted from its original value. If such a guy exists, I hope he also will report "before" and "after" performance data on his car to show the difference between a "good" cap and a "gooder" cap.

Would it be advisable to throw away brand new caps that are in stock which happen to measure the same value as a "good" 11 year old cap which has possibly degraded slightly from it's original EXACT value but is still within manufacturer's tolerance?

light bulb resistance could probably benefit from age analysis and drift from new values, but I'll probably just continue to use them until they stop working...I'm lazy that way...besides, it's a toss-up as to which is more difficult, digging out tar or getting the frickin' headlight ring off. Now, if I ever perfect my device which notifies me the day before a bulb is going to blow, I'll be a happy man, as it is going to eliminate my needing to do performance analysis on bulbs!

I pretty much enjoy a car that starts with 1 or two pulls, has enough air in the tires to not spin a valve stem off, and have well adjusted coils with caps that measure "good" and will run down the road at a good clip...I had no idea that there was so much more to worry about!

Steve, to your question, I say that if it takes a day for you to rebuild one, then the right time to test them is 2 days before an important trip, or whenever performance of the car degrades and a new tank of gas doesn't fix it.

Recommended reference is the ECCT instruction manual available here: https://modeltecct.com/ecct-downloads

Another resource is the FAQ page found here: https://modeltecct.com/faqs

In short: the ECCT capacitor test is very sensitive to leakage resistance and can produce a "POOR" result but does not necessarily mean the capacitor should be replaced. The capacitor VALUE should be the primary metric used to determine if the capacitor requires replacement or not. Capacitor Values of 0.47uF +/- 20% (~0.33uF to 0.56uF) indicate the capacitor does NOT require replacement. Capacitor values of 0uF to 0.22uF should be replaced.

MKossor wrote: ↑

Wed Jul 12, 2023 10:04 pm

The capacitor VALUE should be the primary metric used to determine if the capacitor requires replacement or not. Capacitor Values of 0.47uF +/- 20% (~0.33uF to 0.56uF) indicate the capacitor does NOT require replacement. Capacitor values of 0uF to 0.22uF should be replaced.

Quite Also, from this, I see that your unit does report the actual capacitor value https://modeltecct.com/ecct-features

Scott,

Lamp resistance for LED's should remain relatively static across their lifetime

Luke.

My simple visual/verbal-oriented mind is in awe of you guys who understand and can discuss electronics without a trace of MEGO. I may learn how to rebuild a coil, but that doesn't mean I'll fully understand it.

Clean metal contacts give ultimate testing values .

I’m with Steve. And I did electrical work in the Air Force. Somehow did better on the electrical portion of the aptitude test than the mechanical part. Actually I never got away from it through my automotive career. But deep discussions with wild values makes my eyes glaze over. By the way the first time I ever heard the speculation that electricity flows out the negative and back to the positive was at Chanute Field Tech School.

I am somewhat reluctant to respond to this thread since it has been explained to me several times in the past that I am not seeing what I think I am on other subjects. But I can't resist, so here goes. I have been rebuilding coils for about ten years for my own consumption and have now done somewhere around fifty or so. I have run them on Model T's and Fordson tractors with what I would consider to be success. I am an expert on nothing, but a keen observer and experimenter extraordinaire. Like most others I started out with a multimeter and adjusted for current draw exclusively. I later learned that old capacitors are almost (always) faulty and purchased a Strobospark tester and have used it for many years with confidence. Multi spark and capacitor tests improved the quality of my work and my vehicles ran much better for it. Several years ago I was able to purchase and rebuild two HCCTs and had Bob Cascisa rebuild and re-calibrate the meters on both. One is hand crank and the other is outfitted with a 1/4 hp motor which improves cranking speed consistency. Out of curiosity, and buying Mike Kossor's argument for "time to fire" technology, I then bought an ECCT and began to use that. The results of that purchase have been positive and exactly as he describes. Now for the anomaly. No matter which machine I use, the others don't seem to agree. The ECCT will show a good to excellent multi spark outcome and when the same coil is run on the HCCTs multi sparks will sometimes appear, and vice versa. The Strobospark might go either way. Obviously the test results on all but the ECCT are arbitrary and depend on interpretation and eyesight. Amperage adjustments also vary, sometimes considerably, between the various testing disciplines. To add to the confusion, I have often taken coils off the shelf that tested "good to excellent" in every regard months earlier and re-tested only to find that they had changed somewhat even though they had never been installed and had only been transported from the bench to the cabinet above. I suspect changes in humidity and temperature have an impact on the test results with the more sensitive equipment. I wonder how critical a Ford mechanic would have been back in the '20's, armed with only an HCCT and being paid flat rate to get the car out of the garage as fast as possible.

Well, David, you seem like a guy with some experience and common sense about you. You ask a question which you already know the answer to, and we know that armed with the test methodology available at the time and the significant difference between an old coil and one that he just adjusted on the HCCT, he would have gotten that car out of his shop as quickly as possible, and had a very pleased customer.

With advanced electronics, looking into millisecond type data, it is no wonder that coils do not seem stable across time - because at that level of scrutiny, they aren't. Whether or not TTF it is a superior methodology (and I have no opinion on that - there are plenty of happy customers in a much better position to opine) it is a completely different methodology than in the past with less worry about double sparking or amperage as there is a computer to measure the one thing of concern - TTF (within wider parameters than had been considered previously regarding strict amperage and double spark criteria). You had mentioned that the differences between old technology testing and TTF were arbitrary, and I understand what you mean, and If you were testing for the same thing on all equipment, I'd agree with "arbitrary", but you aren't measuring the same thing(s). With no such technology in place originally, it was those specific attributes which were depended upon to control TTF but not measure it. The HCCT did it's thing at whatever speed you crank - the motor HCCT improved that - the Strobospark tests at 3 different voltages. With care, you can adjust a coil to test exactly on all 3 and still not agree with the TTF system due to a completely different operational test philosophy. I think this quantum improvement in data acquisition and analysis which leads folks to worry excessively about things and see from month to month that performance drifts with humidity, and therefor, they are in for a lot of angst. By and large, those time or humidity dependent attributes which are drifting on electronic test equipment are typically (as you and others have found) to be largely invisible to more primitive test equipment. And, by and large, those small detectable drifts are going to have to become pretty large to be felt by the average butt and by then, would be noticed by a HCCT, too. That's the point - at what level of drift are coils tuned to TTF in need of remediation? If you can test for the drift, but can't feel the impact of the drift, why worry about it? I suppose it depends if you got into the hobby to drive your car, or spend every afternoon dialing everything to the "nth" degree, which I believe is entirely counterintuitive to the whole point of owning and driving 100 year old technology.

I have no doubt that if modern coil testing equipment were to go into the way-back machine and land in the hands of the average mechanic, the total time cars would have made use of wood coils on a magneto would have been exactly 1 model year. Coils would have been shown to notoriously fall out of adjustment at the drop of a hat, and a full-court press would have ensued to find a more "reliable" product, regardless of the fact that those same coils would operate for a very long time providing practical and adequate spark to motor along at 12MPH on a soft dirt road.

There is great benefit to Continuous Improvement in technology but for some practical aspects, some things just don't need to be looked at too closely to perform just fine within designed parameters - 64" LCD TV's have proven that point, as some of the best looking actresses on an old 19" RCA look pretty rough at 2x life-size on a LCD - YIKES!

I have no doubt that coil settings vary in response to environmental conditions as well as changes in input and variations in spark plug and timer condition. One good reason to set TTF as closely as possible is to keep all 4 coils as close to the same as is practical. Good coils in good adjustment could be expected to be the most stable, and with all 4 set the same, it would be less likely that normal day to day variations would cause issues. On spec is almost always best.

I have to agree with what what’s posted above. Some are just looking too close. Dragging a 100+ year old technology kicking an screaming into the present day. While a modern affordable cool tester was definitely needed as HCCT’s are quite scarce I’m betting that if you set up a set of coils on a HCCT or an electronic tester you won’t be able to tell the difference when driving the car.

Guys,

As I understood it Steve was interested about when he should test his coils?

I'm not sure how this latter discussion assists him, and much of it has been said before ad nauseam in threads more suited.

Regarding the efficacy of coils set by TTF; Mike has published the results of empirical testing, it may be of interest to you to look at that here https://img1.wsimg.com/blobby/go/f76807 ... 7559394171

Otherwise in terms of how regularly to test coils it's not clear to me that the methodology of testing should affect that much, except that 'old school' equipment, although the best of its time, will not be as consistent and accurate as what we can have today. With modern equipment you may be able to establish a dataset and forecast more easily a reasonable period between tests for each coil than you otherwise could. Perhaps that will be of interest to some, or perhaps not, but either way I think Steve has, or has access to, a modern tester that would permit it.

To clarify: three posters have suggest annually, or ~3000 miles between coil tests, which seems a reasonable place to start. However if you have an accurate tester and recorded the results of each coil test you may then be able to establish a pattern of deterioration over time that could allow you to better predict when a coil should be tested.

David,

I'm not entirely surprised at your findings of differences between testers, but the apparent change in characteristics of unused coils is interesting. There are of course many variables that could have input to this, but I wonder if you've controlled for these, and whether you've established any pattern?

Luke.

Conditions of use would probably need to be considered as to how long a set of coils might hold a good adjustment. I would expect that a set of coils with accurate adjustment would run satisfactorily the longest under any given type of service. If you have ready access to test equipment, it's not difficult or time consuming to check the coils. If they all check out OK, you're out very little. If they do need adjustment, it's usually not a difficult thing to do, and you'll be rewarded with improved performance, longer point life, and an expectation that the coils will maintain a good adjustment for some time to come. If you don't have ready access to test equipment, maintaining the timer and spark plugs in good order and running on magneto should help preserve a good adjustment.

Yes, I used one of these:

Considering the sage advice above and my own inclinations, I believe I will test before each driving season and before each big trip. If I find that's too much I can cut back. I hope I can take some time next winter to learn coil rebuilding and have half a dozen ready to go if I need them.

I had four Ford script coils rebuilt by Ron Patterson 10 years ago. I have over 10,000 miles on this car, and have never had the lid off the coil box.

That's a good run. I would extend it and maximize engine performance, points, and and timer life by testing and adjusting the coils, or having somone who has the best equipment do it.

(Or you can run 'em to death ... your choice)

I have over 10,000 miles on this car, and have never had the lid off the coil box.

There is a huge difference between a Model T engine that "runs" and a Model T engine that runs well.
Its really difficult to appreciate the latter if you only experienced the former.

The chances all 4 coils have the same dwell time to fire spark and do so consistently after 10,000 is near zero no matter who rebuilt and tuned the coils. If there is no perceivable improvement in engine performance after adjusting all 4 coils for equal and consistent firing time, there are other issues. A warn out timer, improper timer centering about the CAM or spark plug ignition issues for example. It is also possible carburetor/fuel mixture issues or even valve/compression issues can limit Model T engine performance.

It is truly amazing how smooth and strong a Model T engine runs when all these variables are operating properly.

My 0,01 $: I think I (again) will follow Steves example and check my coils every spring for dwell and multispark.

Consider this: back in the day you would most likely have 4 coils made at same day and hence with basicly same electric and magnetic specifications. Hence adjusting on HCCT to singlespark and 1,3 amps would give same dwell.

Today your coils may be made at four different years and some made by K+W and some made by Ford. They can never have the same dwell at same current draw. Thats why ECCT gives more consistant results.

Reviewing the printed literature of years past, indicate to have dry cell used for ignition, the 1.3 amp draw was for battery life.