Adjusting coils

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Adjusting coils

Post by bobt » Wed Feb 12, 2020 3:51 am

Hello. I'm a newb and have a question. Can you adjust coils while the engine is running without getting shocked? Thanks, bobt

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Re: Adjusting coils

Post by Luke » Wed Feb 12, 2020 4:28 am


Although the points are on the low tension side you'll have back emf enough that you'd probably get a shock if you utilise non-insulated tools.

However the bigger question is why would you want to this? To what standard would you measure against?

Ordinarily coils are adjusted outside of the vehicle, via a number of possible different methods, then installed back in the car. This way they can easily be adjusted to a specific, known, criteria.

That said I suppose you could put an AC ammeter in series with each coil on the car and adjust to average current, but I wouldn't recommend it!

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Re: Adjusting coils

Post by Humblej » Wed Feb 12, 2020 7:04 am

Do not adjust your coils yourself! It needs to be done out of the car by someone who has the special equipment and knowledge. This is not a job for a shade tree mechanic with hand tools. Either a modern electronic strobospark, or an origional hand crank coil tester (HCCT), with the knowledge to use them, is absolutely essential.
Last edited by Humblej on Wed Feb 12, 2020 12:48 pm, edited 1 time in total.

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Re: Adjusting coils

Post by Jeff5015 » Wed Feb 12, 2020 9:36 am

I am a newbie too. I adjusted my coils using the ECCT found around here and in the magazine.
What you need is a good sense of electronics and an understanding of what the coil is supposed to do. Then, if you can follow instructions you will be able to tune your coils. Be aware that you can mess things up quite a bit. But like nearly everything else with a Model T, it is all recoverable.

(most certainly out of the car!)

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Re: Adjusting coils

Post by Steve Jelf » Wed Feb 12, 2020 12:33 pm

I agree that coils should be adjusted with the proper equipment by somebody who knows how or can follow directions. The equipment can be Strobo Spark, ECCT, or HCCT, ranging in price from a few hundred to several hundred. If you have just one Model T and don't drive it a lot, you're better of to send your coils to a pro for restoration and adjustment. But your local Model T club may have the equipment and expertise to do the adjustment at little or no cost.
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Re: Adjusting coils

Post by RustyFords » Wed Feb 12, 2020 4:40 pm

I’m just building it into the costs of running my car to outright purchase two new coils per year until I have 8 rebuilt coils. I have six now and will buy a couple more at the end of the year.

Then I’ll have four in the car, two freshly rebuilt ones in the toolbox and two on the bench getting freshened up by me. I bought an ECCT and will soon start learning the intricacies of repairing coils.

I’ll also be able to provide this service to my small local group of T owners for free when they need it.
Last edited by RustyFords on Thu Feb 13, 2020 8:49 am, edited 3 times in total.
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Re: Adjusting coils

Post by bobt » Thu Feb 13, 2020 7:13 am

Thank's for all the great advice. I'm learning and so far have enjoyed my new hobby. Bobt

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Re: Adjusting coils

Post by Original Smith » Sat Feb 15, 2020 9:39 pm

You can do it, but what are you going to gain? No, you are not going to get shocked.

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Re: Adjusting coils

Post by John Warren » Sun Feb 16, 2020 9:40 am

I have adjusted coils with the engine stopped and running, seemes like I do feel something occasionally. The only reason for me doing this is out of desperation, on tours or just trying to get it run. Most of the time I find that the nuts holding the points are not making good contact. Just loosening and tightening them will make them start to work. Some day I want to get a couple of sets of properly rebuilt coils. One of the guys in our club was having continuous problems with the engine running poorly , changed spark plugs, timers, wires moved coils around, and nothing seemed to help. His next step in his mind was an engine rebuild. He went ahead and purchased a properly rebuilt set of coils and WALLA, It runs great! His coils were working but just not right!
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Re: Adjusting coils

Post by Charlie B in N.J. » Sun Feb 16, 2020 10:01 am

As a former buzz box guy I was amazed at the improvement in operation with properly tuned coils. My '23 started dead cold on mag hand cranking after they were installed.
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Re: Adjusting coils

Post by Fire_chief » Sun Feb 16, 2020 10:49 am

I was lucky enough to have the opportunity to beta test the I-Timer. I trailered my 14 touring to Mikes house, where he used the ECCT to adjust my coils. There was a noticeable difference in the way it ran. We then installed the I-Timer, and went for another ride. Again, there was a great difference in the way it performed.
I now have 5 of my T's set up with rebuilt coils and I-Timers. It's expensive, but well worth it.

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Re: Adjusting coils

Post by MKossor » Sat Feb 29, 2020 5:22 pm

Bobt, Short Answer: Adjusting coils on a running Model T is NOT recommended for 2 main reasons:
1. You cannot effectively adjust coils for good engine performance
2. You CAN get shocked touching the coil points with the coils operating

Long Answer:
Good Model T engine performance requires properly timed spark ignition when each piston approaches Top Dead Center (TDC). Proper ignition timing depends on:
1. Timer in good condition (Good, clean contacts)
2. Timing cover properly aligned (centered) about the CAM shaft
3. Coils adjusted for equal and consistent firing time
4. Good Spark plugs properly gaped (ex. Champion X, 0.025" gap)

Properly adjusted coils (Item 3) means all 4 coils are adjusted to fire spark with equal delay and consistency when the Timer activates the coils. To achieve properly adjusted coils, the coil point contacts must be clean and void of pitting. The contacts must have proper point geometry (that is, properly aligned contacts which are parallel with each other when closed) Proper point geometry often requires washers under the upper point bridge stand-offs to ensure the point contacts close parallel with one another Before point contact adjustment is attempted.
Coil adjustment depends upon 3 main variables:
1. Coil point gap
2. Lower Vibrator spring tension
3. Upper cushion Spring Tension

The initial recommended point gap is 0.030". The Vibrator spring tension is adjusted to achieve the desired firing time. The cushion spring tension is adjusted to achieve good firing consistency. All 4 coils are adjusted for the same firing Time and firing consistency. Coil point adjustment is most effectively done one coil at a time by actually measuring the time it takes the coil to fire spark when commanded to do so by the timer. Here are links to videos which demonstrates this process using a tool I developed:

An alternate method of coil adjustment monitors the average primary coil current while it is firing a periodic series of sparks; like it does in normal operation. In this scenario, the average coil current is an indirect approximation of coil firing time. Adjusting the vibrator spring tension of each coil for equal average coil current reading indicates each coil is firing spark in approximately the same time. You could rig an Ammeter to monitor average coil current in the car but it is not as simple as installing it in series with the coil box power lead since you would not be able to associate average coil current to a particular coil. You could alternately install an Ammeter in series with each timer wire to alternately monitor individual coil average current but there is another caveat; each coil must fire a single spark as it is operating otherwise, the average coil current does not accurately represent coil firing time. Therefore, you need a way to see the time behavior of the sparks as they fire (not sure how listening to the engine idle would be effective in detecting double sparking coil operation) if the coil is double sparking; it can be remedied by adjusting the cushion spring tension. This was solved by sending the coil spark to a rotary spark gap with equal spacing to the ground electrode as was done on the Hand Cranked Coil Tester. So even if you were monitoring individual coil average current while adjusting the coil points in an operating car, not sure that would be a viable method to achieve good results.

Regarding the question: Can You Get Shocked Touching Operating Model T Coil Points?
The answer is YES. Here is the measured voltage that develops across a Model T coil operating on 12V battery during operation, note that the peak voltage reaches 200V but only for a very short duration:
Coil Point Voltage.JPG
Will you get shocked? The answer is; It depends. The variables include:
1. The voltage develops across the coil point contacts so touching both point elements present a shock hazard.
2. The voltage also develops between one point element and Engine/body ground so touching that point element and Engine/body ground presents a shock hazard, which could be even more dangerous if electrical current passes from one hand to the other as it travels across the chest.
3. How moist your skin is a factor in making good electrical contact with the coil point elements and/or Engine/body ground.
4. How tightly you touch/squeeze the coil points and/or Engine/body ground is a factor in making good electrical contact with the coil point elements and Engine/body ground.

This may explain why you received varied input others based on their experience.
I-Timer + ECCT Adjusted Coils = Best Model T Engine Performance Possible!

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Re: Adjusting coils

Post by Duey_C » Sat Feb 29, 2020 10:26 pm

From the outfield for Newb's and shade tree-ers. Chastise me if you wish yet bare with me for a moment. :)
The answer is yes Bob.
Even flakey, dirty, crummy, half dead coils can be fiddled with in the coil box, on a running engine with your bare fingers!
Just fiddle with the moving point until that coil decides whether or not it's gonna pick it up.
THEN ya fiddle with the adjusting nut, listen to the sound and fiddle with the moving point again until it picks it up.
I have never been shocked up on top. If ya get shocked up on top, there's somethin' wrong.
You guys have NEVER done that before? Really? C'mon... ;)
I've done that on my buddy's truck and other engines many, many times. :)
Interesting what your thread brought up to my noggin' Bob. I think I'll have some coils done-up for my friend's TT as a gift.

With that said:
You will not believe the transformation of an engine that has properly adjusted HOT coils! Holy moley!
It's amazing!
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Re: Adjusting coils

Post by Moxie26 » Sun Mar 01, 2020 9:17 am

Hey Dewey...... I guess you can do all the fiddling you want, and all depends what kind of song you want. Lol.....

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