Coil trouble shooting

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Model T Ford Forum: Forum 2017: Coil trouble shooting
Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Ledbetter on Sunday, September 10, 2017 - 11:02 pm:

Just put a new wiring harness and coil points on my 26. I set the gaps on the points but nothing else. It ran great for the past week. It was almost like a whole new breath of life into the old girl. But I took it out today and it seemed to miss slightly at speed and didn't have much power compared to what it was just a couple days ago. When I went to trouble shoot the coils all buzzed about the same. Did a quick compression check that came up good. So I started looking closer at the coils. One will jump a spark with about a 3/8 gap. The others will only jump on contact. This doesn't seem right to me. Am I on the right track or way off.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erich Bruckner, Lake Oswego, OR on Sunday, September 10, 2017 - 11:17 pm:

Sounds like a job for a strobospark or similar tester. The correct adjusting of the top components on coils is not something that can be done by eye, ear, or feeler gauge. Do you have access to anyone around who has good test equipment and know how?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Ledbetter on Sunday, September 10, 2017 - 11:38 pm:

Not that I have found. I am in the Springfield mo area. I have talked to my local contacts in the club but just dead ends. I'd be willing to make a little bit of a drive to get them straightened out.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steven Thum on Monday, September 11, 2017 - 12:23 am:

Aaron,
I live in St.Louis and own a strobo spark. I have rebuilt hundreds of coils. If you get to St. Louis I would be happy to check out your coils and set the points. If you a interested pm me and I will email you my contact info.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Michael Deichmann, Blistrup, Denmark on Monday, September 11, 2017 - 03:42 am:

Aaron, it is most likely the 90+ years old condenser in the coils that no longer is up for the job. Take steves offer and even let him rebuild them with a new condenser and adjust. You will get a completely new car!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erich Bruckner, Lake Oswego, OR on Monday, September 11, 2017 - 12:37 pm:

What Michael said......


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erich Bruckner, Lake Oswego, OR on Monday, September 11, 2017 - 12:44 pm:



Correctly rebuilt coils will make all the difference. You won't regret it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Ledbetter on Monday, September 11, 2017 - 08:40 pm:

Pm sent Steven. I'd be thrilled if they did make all the difference Erich. It would be nice if I could trust it to go on drives with the club. Maybe even drive it to work occasionally.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Duey_C on Monday, September 11, 2017 - 09:39 pm:

Aaron, truth be told? I had four coils that functioned OK in the 18. Ran really good after resurrection.
I had cleaned the points and tested/adjusted the coils with what I have. My fingers, my ear and some wire.
Then I had four coils rebuilt correctly by Andy L. and I turned the carb DOWN/closed one full turn to get it to run correctly after install of the rebuilt coils.
True story. Knocked me over with a feather and OH for the free starts!
I thought it was BS. Nope. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Monday, September 11, 2017 - 11:27 pm:

What is sad is when someone converts the car to a distributor before they ever get the single experience of running with properly setup coils. I had the pleasant experience last week in Michigan of setting up my strobo-spark and doing some coils for a few of the 15 or so cars on a small tour. One guy had problems with his car since forever and was just beaming at the end of the tour. He thought I was a miracle worker but it was really that he had never actually done anything before other than gap them and was not at all savvy with regard to the cushion spring on the points. He did replace the capacitors with the correct items so he got close but he sure was a happy camper at the end of the tour having driven it for several days with amazement.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steven Thum on Tuesday, September 12, 2017 - 11:51 am:

Aaron,

Emailed you with my phone number. Call me. If you bring the coils to me I can show you how they run a car verses rebuilt coils.

Thanks
Steven


Top of pagePrevious messageNext messageBottom of page Link to this message  By kep on Wednesday, September 13, 2017 - 05:00 am:

I have this exact problem with "new" coils. Can anyone tell me what the solution was? Doesn't appear to be an open secondary


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Wednesday, September 13, 2017 - 07:51 am:

I'm not sure now, but a while back, there were "New" coils on the market that were not adjusted properly. Apparently, even some vendors don't believe that coils must be set up properly to function correctly on magneto. It takes more than setting a point gap!

Word to the wise for newbies: Don't mess with the point adjustment on coils unless you have the proper equipment to set them up properly! The point gap isn't even REAL important! If your car isn't running quite right, it is not likely the coil point gap. There is a delicate balance in spring tension between the lower point spring and the upper cushion spring. You can't fix it without the proper equipment. Attempting to set the point gap will most likely upset the cushion spring tension and result in a worse running car. Conversely, having a set of coils set up properly will make a T seem like it has a turbocharger.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Kossor - Kenilworth, NJ on Wednesday, September 13, 2017 - 12:20 pm:

Hal, very well stated. Stories of setting up coil points by eye or ear with success are either tails of luck or lack experience with Model T engine performance using properly adjusted coils for comparison.

Aaron, Not sure what you mean by: "The others will only jump on contact" Coils should be able to produce a spark that jumps a 1/4" gap (from high voltage terminal to timer terminal) when the coil point contacts open (break contact). A bright arc flash at the coil points when they open but no spark across the 1/4 gap indicates a defective internal capacitor/condenser. Note that coils must always be tested with proper spark gap. It is NOT recommended coils be operated with spark gaps greater than 1/4" to prevent internal arcing which may cause permanent damage to the coil. In such a case, the coil points still operate normally but the spark occurs internal to the coil before it can jump the 1/4" spark gap (no spark). The reason coils are tested with a 1/4" spark gap at atmospheric pressure is that it simulates typical 0.025 spark plug gap under compression.


Top of pagePrevious messageNext messageBottom of page Link to this message  By James A. Golden on Wednesday, September 13, 2017 - 12:40 pm:

When all the coil point adjustments are properly set, you will find the coil will buzz with very close to the proper 1.3 Amps AC Current reading.

The proper tool for adjusting the vibrator spring tension is a Gap Gauge, previously used by telephone employees to adjust the switching relays for phone calls.

The proper reading appears to be 75 grams to open the points.

Here is an example.

Gap


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Wednesday, September 13, 2017 - 12:57 pm:

Really? That's the "Proper" tool?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Wednesday, September 13, 2017 - 01:10 pm:

When you test for spark jump do not buzz the coil with the spark gap wider than 1/4 inch. If it doesn't jump fix the coil. A spark will jump the closest path to ground and if the spark plug is bad or the wire is open it could jump inside the coil or inside the coil box resulting in a carbon path. Then even if the coil is properly adjusted and you have the proper spark gap it will take the easiest ground and your coil box will need to be repaired or the wood on the coil cleaned and/or replaced.

I wonder where Ron Patterson is? I would expect an answer from him!
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Wednesday, September 13, 2017 - 04:58 pm:

Yeah, I figured we'd hear from him too.

Newbies, your coils need to be set up on a hand cranked coil tester or a Strobospark (or if you ascribe to Mike Kossor's theory, an ECCT). AC buzz boxes won't cut it, and neither will setting the spring tension to some particular load as measured with a scale. Somebody's gonna have to show me some dyno data 'fore I'm believing THAT.


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