Ignition failure

Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration
Model T Ford Forum: Forum 2017: Ignition failure
Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Sunday, November 12, 2017 - 02:10 pm:

The other day I experienced the familiar sensation of driving on three cylinders: no pep. This time it wasn't a spark plug. The #2 coil was buzzing but not sparking the plug. From what I've read, this means a failed condenser or an open secondary. Either way, it calls for digging into the guts of the thing, not just a simple adjustment. Is that correct?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Sunday, November 12, 2017 - 03:58 pm:

You are correct. It is good to have some extra coils tuned and ready to plug in. Then if this happens, you can continue on and try to fix your bad coil later.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Sunday, November 12, 2017 - 05:56 pm:

Steve if it is a bad secondary winding there is no fixing that. Try replacing the capacitor see if that helps


Top of pagePrevious messageNext messageBottom of page Link to this message  By Michael Pawelek Brookshire, Texas on Sunday, November 12, 2017 - 06:00 pm:

Bob, Are you telling us you don't rewind your secondaries? :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger - Wyoming on Sunday, November 12, 2017 - 07:25 pm:

Wow...I'd sure check the secondary winding with an OHM meter first, before replacing the capacitor...might save a bunch of work.

A more obscure failure is an insulation failure where there is an arc internally and that will take a Meggar to check for. This is a wily failure that can really throw you a loop when the coil is rebuilt, all resistances are good, capacitor is replaced and.........no spark at the tester.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Monday, November 13, 2017 - 01:39 pm:

Michael... don't have the patience to rewind secondary coils, knit one, pearl two ???? 3200 ohms is ballpark value for Ford built coils....rather spend time making pierogies....lol.😁😎


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Schreiber- Santa Isabel Ecuador on Monday, November 13, 2017 - 04:47 pm:

Ahhhh, pierogis.....A Christmas Eve staple as a kid :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Monday, November 13, 2017 - 05:05 pm:

I have a coil that reads zip between the two terminals and still sparks. Whot up?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Lenney Glenn on Monday, November 13, 2017 - 05:47 pm:

Charlie, what type vom are you using? Some very early digital meters were unreliable when measuring resistance of an inductive device.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger - Wyoming on Monday, November 13, 2017 - 10:43 pm:

"the two terminals"

which two terminals?
There are 5 different places to place a probe
Here is a great illustration and I'd give credit if I knew where I got it or who put it together...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Monday, November 13, 2017 - 11:29 pm:

That's an excellent reference. It's going in my How to file.

It turned out that this was a false alarm, and I don't know why. I was going to send the suspect coil to Ron Patterson, but I thought first I'd make sure it was the problem. I put it in the car and cranked 'er up. The screwdriver-to-head test showed spark to all four plugs. I tried moving the coil to different positions in the box and got the same results. I went for a test drive and the car ran normally, including going up a couple of little hills. I have no clue why the car was running on three cylinders yesterday, or how I "fixed" it. I could speculate on possible reasons, but I really don't know.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Hughes, Raymond, NE on Monday, November 13, 2017 - 11:45 pm:

Probably a bad connection between the coil and coil box. By removing the coil and then replacing it, it rubbed off some corrosion, or just sits in the box a little differently and so makes a good connection. This might be a temporary fix.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Kossor - Kenilworth, NJ on Tuesday, November 14, 2017 - 09:07 am:

I agree Steve, although a couple comments:

Problem Causes, the A-B resistance readings for Condenser Open and Shorted are reversed. Open should read infinity Ohms and shorted should read 0 Ohms

Cushion Spring Gap: Ford recommended 0.005" which correlated well with the test data I took. There was no benefit beyond 0.006" in my test data. In fact, excessive gap (>0.010") only makes it more difficult to balance cushion spring tension and vibrator spring tension for consistent firing time. Some coil points are made with in excess of 0.025" gap and can be a real bear to adjust for consistent firing time because the contacts must break clean properly without the benefit of the limit rivet head causing the abrupt contact break; defeating the entire purpose of having a limit rivet!

Point Gap: 0.031" is a good default value, however, this may need to be increased or decreased to achieve the proper balance between cushion spring tension and vibrator spring tension, especially so on points that have excessive cushion spring gap as was just described when the purpose of the limit rivet is defeated.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Tuesday, November 14, 2017 - 09:31 am:

C & D. Digital meter.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger - Wyoming on Tuesday, November 14, 2017 - 10:07 am:

Charlie

check the range you had set on your meter and try again


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger - Wyoming on Tuesday, November 14, 2017 - 10:14 am:

Mike

Respectfully, please look at the diagram again...under Connections/OHM readings, the condenser OHM values are correct. Under Problem Causes - Symptoms, it gives the reason for the observation (heavy blue arc). In other words, there is no error on the diagram...I think you've misread or misunderstood it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Kossor - Kenilworth, NJ on Tuesday, November 14, 2017 - 11:04 am:

Scott, Connections/Ohm Readings section is correct; A-B should measure infinity Ohms with points open. I believe my comment regarding A-B resistance readings being reversed is correct.

Problem Causes-Symptoms the A-B resistance readings for Condenser OPEN (A-B 0 Ohms w/points open) is wrong. If the condenser is OPEN, the resistance reading should be infinity Ohms as there is no path for current flow.

Likewise; the A-B resistance for Condenser SHORTED (A-B infinity Ohms w/points open) is wrong. If the condenser is SHORTED, the resistance reading should be 0 Ohms with the points open because the capacitor (connected across point contacts A-B is SHORTED; i.e. always conducting current with low resistance by definition; 0 Ohms.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger - Wyoming on Tuesday, November 14, 2017 - 11:20 am:

Mike

you read it right and I did not! HA!

thanks


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Kossor - Kenilworth, NJ on Tuesday, November 14, 2017 - 12:43 pm:

NP Scott, it was worth the review. Certainly don't want to misinform anyone, especially the new folks.

It is a great reference but don't recall who the author JMC is. Perhaps someone else does and can pass along my comments so the error can be corrected.


Add a Message


This is a private posting area. Only registered users and moderators may post messages here.
Username:  
Password:

Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration