Coil question regarding Fun Projects great equipment and odd problem with coil.

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Model T Ford Forum: Forum 2013: Coil question regarding Fun Projects great equipment and odd problem with coil.
Top of pagePrevious messageNext messageBottom of page Link to this message  By Darren J Wallace on Wednesday, January 23, 2013 - 12:31 pm:

I'm not real savvy on electrical theory and applications but I do understand some things :-)
I have a bit of a stumper:
I borrowed a John Regan Stroboscope coil tester from a friend who bought one last year and I love it! It's much easier to use than my HCCT.
I also own one of John's nifty little coil testers for checking secondaries.
When I have a coil which passes the "beep" test on the little secondary tester,and I have replaced the capacitor with the correct one,and properly rebuild the coil unit, I occasionally get a coil which will work for a short time,and then never will make sparks again on either the Stroboscope or my HCCT. All gage settings on the Stroboscope are within tolerance:cap leakage,cap value,running current,coil vibrates but produces no high voltage.
I've rebuilt many coils and this particular problem occurs once in a while.
Any thoughts? Is said coil junk?

Thanks guys!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Vaughn on Wednesday, January 23, 2013 - 12:38 pm:

Darren, The coil acting like you describe, most probably has an open secondary and is sparking internally. What happens is that initially the open area is small enough that the spark is able to jump and continue to work, but after a while the gap burns larger and it is unable to jump the gap and the spark will go to ground internally.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Thode Chehalis Washington on Wednesday, January 23, 2013 - 12:56 pm:

Darren,
Yes, it is likely junk. This is from:
http://www.mtfca.com/discus/messages/257047/331418.html?1356970583

By Jim Thode Chehalis Washington on Sunday, December 30, 2012 - 12:04 pm:

Don't forget internal arcing will make a coil not rebuildable and and it will not show up till the coil is powered up and the spark tested.
Jim

By Ron Patterson-Nicholasville, Kentucky on Sunday, December 30, 2012 - 01:25 pm:

Jim
Your correct and you will find that latent fault in one out of every 75-100 coils during rebuilding.
You detect this fault during the rebuilding process, when the old capacitor is removed and before the new capacitor has been installed, using a 1000volt a Megger connected across the two windings.
Ron the Coilman

By Jim Thode Chehalis Washington on Sunday, December 30, 2012 - 02:29 pm:

Ron,
If a person does not have a 1000volt Megger you just install the new cap without soldering and test the coil on the HCCT before soldering, potting and installing the lid.
Jim

By Erich Bruckner, Vancouver, WA on Sunday, December 30, 2012 - 03:07 pm:

I also learned the hard way to do a final test of operation in the coil tester BEFORE repotting with tar.


Jim


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Wednesday, January 23, 2013 - 12:59 pm:

Mike has it correct. In addition a coil might have everything correct including "beeping" with an intact secondary winding but the coil has in the past been powered up with only a wide gap to jump like when buzzing a coil with no spark plug wire and spark plug connected. When then presented with a gap to jump - that coil instead will have the spark jump internally inside the box because there is a carbon track in there for it to follow and it prefers that. Unfortunately this is a fatal event for a coil. I have seen folks get fooled by testing coils on even an HCCT that had its gap set too close at say 3/16 or so and the coil seems to work somewhat better but this is not a good coil. A good coil will jump a 1/4" gap and that is what your HCCT should be set to and is what the Strobo-Spark is set to.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Wednesday, January 23, 2013 - 01:00 pm:

OOPS I was typing when Jim was.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Garnet on Wednesday, January 23, 2013 - 03:47 pm:

Kind of off topic but what kind of coils does your Queen have Darren (not having ever seen one)?

Regards,
Garnet


Top of pagePrevious messageNext messageBottom of page Link to this message  By Darren J Wallace on Wednesday, January 23, 2013 - 04:30 pm:

Thanks very much guys!
I will now test future coils without soldering the cap and try it first before continuing with the rest of the repair.This is very good to know.Thanks again!

Hi Garnet.
Thanks for asking about my 2nd most important Queen! 1st being the wife!
Originally it used a single coil unit made by Schug Electric(Detroit) and powered both spark plugs at the same time,even though only 1 spark plug is actually doing anything.
Currently,I've been using a dual Schug unit I found years ago on ebay that looks exactly the same except for the fact that it has two separate vibrator coils all potted in one box and the switch mounted to the coil box.The single unit has a mahogany case while the twin unit is oak.Internally, they're built like a brick sh*thouse compared to model T coils.I believe the dual unit was designed to power a 4 cylinder engine as well as a two cylinder like my car.
The reason I chose to change it was that I was afraid years ago (with the engine being unrestored,and known poor valve timing) that it might fire a plug at the wrong time with bad results to motor an/or me. My grandfather owned the car before me and he powered it with 2 model T coils for years.To mount the bigger Schug unit, I made a brass adapter plate to mount to the firewall so it used all the original wood screw holes and I didn't have to alter anything on the car.

John, I haven't forgotten about you regarding the Schug lettering so hopefully I can take the coil box off of the car and get you the specs you asked for.Sorry it has been so long.


dual unit restored:


I've since made all new vibrator components out of blued spring material and new points robbed from new T points. This coil unit works very well. The switch allows you to run on two different sets of batteries,and if you were really hard pressed to get home,the two sets can be used at the same time in the "2 o clock" position.
Dual unit on firewall as it is presently:


Someday, I would like to restore the original single coil unit and see how it would work,as the engine is timed correctly now.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Darren J Wallace on Wednesday, January 23, 2013 - 04:30 pm:

Thanks very much guys!
I will now test future coils without soldering the cap and try it first before continuing with the rest of the repair.This is very good to know.Thanks again!

Hi Garnet.
Thanks for asking about my 2nd most important Queen! 1st being the wife!
Originally it used a single coil unit made by Schug Electric(Detroit) and powered both spark plugs at the same time,even though only 1 spark plug is actually doing anything.
Currently,I've been using a dual Schug unit I found years ago on ebay that looks exactly the same except for the fact that it has two separate vibrator coils all potted in one box and the switch mounted to the coil box.The single unit has a mahogany case while the twin unit is oak.Internally, they're built like a brick sh*thouse compared to model T coils.I believe the dual unit was designed to power a 4 cylinder engine as well as a two cylinder like my car.
The reason I chose to change it was that I was afraid years ago (with the engine being unrestored,and known poor valve timing) that it might fire a plug at the wrong time with bad results to motor an/or me. My grandfather owned the car before me and he powered it with 2 model T coils for years.To mount the bigger Schug unit, I made a brass adapter plate to mount to the firewall so it used all the original wood screw holes and I didn't have to alter anything on the car.

John, I haven't forgotten about you regarding the Schug lettering so hopefully I can take the coil box off of the car and get you the specs you asked for.Sorry it has been so long.


dual unit restored:


I've since made all new vibrator components out of blued spring material and new points robbed from new T points. This coil unit works very well. The switch allows you to run on two different sets of batteries,and if you were really hard pressed to get home,the two sets can be used at the same time in the "2 o clock" position.
Dual unit on firewall as it is presently:


Someday, I would like to restore the original single coil unit and see how it would work,as the engine is timed correctly now.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Darren J Wallace on Wednesday, January 23, 2013 - 04:34 pm:

sorry for the double post :-(


Top of pagePrevious messageNext messageBottom of page Link to this message  By Darren J Wallace on Wednesday, January 23, 2013 - 04:48 pm:

Another piece of almost useless trivia...
Every Schug coil unit I have seen that retains it's original brass ID tag,have all the information boxes left blank, regarding model,volts,etc..


Top of pagePrevious messageNext messageBottom of page Link to this message  By Garnet on Thursday, January 24, 2013 - 08:07 pm:

Thanks for the explanation Darren and for the pictures also. I've seen many photos of your Queen over the years but don't recall seeing any of the ignition. And yes, I'm aware of your wedded Queen also. You are a man of many blessings.

Garnet

PS: If you have any (and I mean ANY) warm weather to spare out East, can you send some of it out West please!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Darren J Wallace on Thursday, January 24, 2013 - 08:32 pm:

Thanks for the very kind words Garnet!
-20 C here right now....how much do want again.....:-)
I hear you guys are getting hammered out there!


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