The Ford Barn

Mike B · 06-14-2010, 01:14 PM

I'm trying to get spark on a 221, points look brand new, no pitting, discoloartion/ect and they are both opening and closing. Gap if roughly .014...tough to get a feeler gauge in there (least the ones I have)

I pulled the coil off and did a "back yard"check on the condenser with my volt meter set on ohms, the condenser resistance climbed quickly to infinity, I grounded the condenser out several times and repeated the test, and each time the condenser would hold the voltmeter"charge"...I realize this isn't and exact science, but one I've used successfully in the past.

Anyways, with the coil out and ohming between the "spring" on the underside of the coil (diver/helmetdistributor) and the inputof the coil, I get .7 ohms, I understand this is low, but would it allow the coil not to fire?

I get an open/infinite reading on the sping loaded contact for the rotors to both the "spring" on the underside of the coil as well and the input of the coil.

I used an old 6v battery I had from garden tractor off my charger at 6volts, and have full 6 volts on the coil while cranking.

Thanks

Bruce Lancaster · 06-14-2010, 01:58 PM

In my experience, those total failure modes are not the way they generally go. They continue to function when cold and progressively lose power/start misfiring as they heat up. Once this starts deterioration progresses rapidly, but the blasted things will continue to make sparks when cold.

JM 35 Sedan · 06-14-2010, 02:05 PM

These old original ignition coils, made back in the day, used magnet wire insulation that is considered to be greatly inferior to the wire insulating materials used in manufacturing of electric coils today. It's my opinion that these coils can and most likely will short between turns in the windings, especially when the coil heats up. The shorted turns/windings in a coil can get so hot that they will often burn and produce open windings. To upgrade your coil and be on the safe side, it's also my opinion that having a coil rewound with modern insulated magnet wire is a smart move. During the rewinding operation the number of coil turns and wire size/gauge could be tweaked a little to produce a hotter (higher voltage) spark at the plugs. I believe that Skip Haney in Punta Gorda, FL, provides the best service available in the USA for rebuilding these old coils, JM

Mike B · 06-14-2010, 02:26 PM

Thanks gentlemen, I agree,once I get this on the road I should have the coil re-wound for reliability sake, but as of know I'm just trying to get things figured out...hate to spend much moneyon something that will just sit for another 6 months...ya...I'm tight

rotorwrench · 06-14-2010, 02:30 PM

Shorting between windings can cause the low Ohms reading you are getting too. A condenser can charge up but then leak through enough so as not to get a full charge. If you keep a few condensers around that you know will build and hold a good charge then you can feel confident that you can eliminate that as a problem during an operational test like yours. Otherwise it is still a guess as to which part isn't doing a good job. Coil tests were always performed after the coil was warmed up for a few minutes by the old testers they used to use. You can warm one up by applying voltage for a few minutes then test the Oms reading again.

G.M. · 06-14-2010, 03:59 PM

Sponsored Links (Register now to hide all advertisements)

I doubt you had 6 volts at the coil when cranking with an old 6 volt lawn tractor battery. G.M.

Mike B · 06-14-2010, 04:11 PM

Quote:

Originally Posted by G.M.

I doubt you had 6 volts at the coil when cranking with an old 6 volt lawn tractor battery. G.M.

You may have missed it, but I had the battery hooked up to my charger.

Ross in East Texas · 06-14-2010, 04:51 PM

If you know someone with a condenser tester, take all of your old condensers and have them tested. I rebuild antique Cushman scooter engines and the old magnetos are notoriously troublesome and the new reproduction parts are not always the best quality. I finally located and bought a real condenser tester that will read the mfd capacity as well as a leakage test. Now I can verify if that old condenser needs to be trashed or to keep. If you are close to Longview, TX just bring them by and I will test them for you.

Mike B · 06-14-2010, 05:02 PM

Apreciate the offer Ross, but I'm on the left Coast

I'll probably get a condenser for now, they're inexpensive enough anyways.

Thanks.

George/Maine · 06-14-2010, 05:03 PM

If the coil were to short out you would draw more current and put it across resister and lose coil voltage.
Test your coil. Test you battery will it light a head light?
Next hook coil neg to neg battery.now with pos grd.Take the conderser with pig tail and hook to coil.Now take the wire from coil hot common wire 1/4 inch from grd. Now if you just touch the condenser to grd you should see it spark,no need to use point now. You could do the with any 6 volt coil.With a stock you may need resister.
Use the ohms scale to see if points make and brake after test should work.

06-14-2010, 01:14 PM	#1
Mike B Senior Member Join Date: May 2010 Location: Oakdale,Ca Posts: 1,323	In general, when coils go bad, do they short out, or open up? I'm trying to get spark on a 221, points look brand new, no pitting, discoloartion/ect and they are both opening and closing. Gap if roughly .014...tough to get a feeler gauge in there (least the ones I have) I pulled the coil off and did a "back yard"check on the condenser with my volt meter set on ohms, the condenser resistance climbed quickly to infinity, I grounded the condenser out several times and repeated the test, and each time the condenser would hold the voltmeter"charge"...I realize this isn't and exact science, but one I've used successfully in the past. Anyways, with the coil out and ohming between the "spring" on the underside of the coil (diver/helmetdistributor) and the inputof the coil, I get .7 ohms, I understand this is low, but would it allow the coil not to fire? I get an open/infinite reading on the sping loaded contact for the rotors to both the "spring" on the underside of the coil as well and the input of the coil. I used an old 6v battery I had from garden tractor off my charger at 6volts, and have full 6 volts on the coil while cranking. Thanks

06-14-2010, 01:58 PM	#2
Bruce Lancaster Member Emeritus Join Date: May 2010 Location: Madison, NJ Posts: 5,230	Re: In general, when coils go bad, do they short out, or open up? In my experience, those total failure modes are not the way they generally go. They continue to function when cold and progressively lose power/start misfiring as they heat up. Once this starts deterioration progresses rapidly, but the blasted things will continue to make sparks when cold.

06-14-2010, 02:05 PM	#3
JM 35 Sedan Senior Member Join Date: May 2010 Location: Near Rising Sun, Maryland Posts: 10,858	Re: In general, when coils go bad, do they short out, or open up? These old original ignition coils, made back in the day, used magnet wire insulation that is considered to be greatly inferior to the wire insulating materials used in manufacturing of electric coils today. It's my opinion that these coils can and most likely will short between turns in the windings, especially when the coil heats up. The shorted turns/windings in a coil can get so hot that they will often burn and produce open windings. To upgrade your coil and be on the safe side, it's also my opinion that having a coil rewound with modern insulated magnet wire is a smart move. During the rewinding operation the number of coil turns and wire size/gauge could be tweaked a little to produce a hotter (higher voltage) spark at the plugs. I believe that Skip Haney in Punta Gorda, FL, provides the best service available in the USA for rebuilding these old coils, JM __________________ *John* *"Never give up on what you really want to do. The person with big dreams is more powerful than one with all the facts". Albert Einstein* Last edited by JM 35 Sedan; 06-14-2010 at 02:10 PM.

06-14-2010, 02:26 PM	#4
Mike B Senior Member Join Date: May 2010 Location: Oakdale,Ca Posts: 1,323	Re: In general, when coils go bad, do they short out, or open up? Thanks gentlemen, I agree,once I get this on the road I should have the coil re-wound for reliability sake, but as of know I'm just trying to get things figured out...hate to spend much moneyon something that will just sit for another 6 months...ya...I'm tight

06-14-2010, 02:30 PM	#5
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,436	Re: In general, when coils go bad, do they short out, or open up? Shorting between windings can cause the low Ohms reading you are getting too. A condenser can charge up but then leak through enough so as not to get a full charge. If you keep a few condensers around that you know will build and hold a good charge then you can feel confident that you can eliminate that as a problem during an operational test like yours. Otherwise it is still a guess as to which part isn't doing a good job. Coil tests were always performed after the coil was warmed up for a few minutes by the old testers they used to use. You can warm one up by applying voltage for a few minutes then test the Oms reading again. Last edited by rotorwrench; 06-14-2010 at 02:45 PM.

06-14-2010, 03:59 PM	#6
G.M. Senior Member Join Date: May 2010 Location: Florida and Penna. Posts: 4,471	Re: In general, when coils go bad, do they short out, or open up? Sponsored Links (Register now to hide all advertisements) I doubt you had 6 volts at the coil when cranking with an old 6 volt lawn tractor battery. G.M. __________________ www.fordcollector.com

06-14-2010, 04:51 PM	#8
Ross in East Texas Senior Member Join Date: May 2010 Location: Longview, Texas Posts: 282	Re: In general, when coils go bad, do they short out, or open up? If you know someone with a condenser tester, take all of your old condensers and have them tested. I rebuild antique Cushman scooter engines and the old magnetos are notoriously troublesome and the new reproduction parts are not always the best quality. I finally located and bought a real condenser tester that will read the mfd capacity as well as a leakage test. Now I can verify if that old condenser needs to be trashed or to keep. If you are close to Longview, TX just bring them by and I will test them for you. __________________ Ross Murphy 1939 Ford Standard Coupe

06-14-2010, 05:02 PM	#9
Mike B Senior Member Join Date: May 2010 Location: Oakdale,Ca Posts: 1,323	Re: In general, when coils go bad, do they short out, or open up? Apreciate the offer Ross, but I'm on the left Coast I'll probably get a condenser for now, they're inexpensive enough anyways. Thanks.

06-14-2010, 05:03 PM	#10
George/Maine Senior Member Join Date: May 2010 Location: Mid coast Maine Posts: 1,878	Re: In general, when coils go bad, do they short out, or open up? If the coil were to short out you would draw more current and put it across resister and lose coil voltage. Test your coil. Test you battery will it light a head light? Next hook coil neg to neg battery.now with pos grd.Take the conderser with pig tail and hook to coil.Now take the wire from coil hot common wire 1/4 inch from grd. Now if you just touch the condenser to grd you should see it spark,no need to use point now. You could do the with any 6 volt coil.With a stock you may need resister. Use the ohms scale to see if points make and brake after test should work.