no spark... where to start ?

J

Jake's 40

Junior Member
FB:
ran a couple of searches but I either get WAY too many results or none at all.
so...
symptom: no spark @ the plugs.
history: did a boatload of work to the car about 18 months ago when a neighbor was breathing down my neck to buy the car. (turns out he was blowing smoke up my ... but that's another story)

ignition parts changed:
coil (Carpenter)
wires
caps
overhauled dizzy (don't remember who)

she fired right up and ran good but has been sitting since.
attempted to start a couple of weeks ago but "no soap". in poking around I forgot that the ignition was was on and the coil was HOT! let it cool down but still no go. thinking the coil might be fried I ordered a NOS MotorCraft ($135)
still nothing.
installed a NOS condenser
still nothing.
I do get 6V at the coil.

waving the white flag.
input appreciated.
TIA
jerry
 
No spark after sitting is often oxidation on the points, easily cleaned with some fine wet/dry paper. Leaving the power to the coil for an extended period of time can burn up at least 1 set of the points.
With a car that has an ammeter, if you don't see the needle wiggle while turning the engine over is a good indication of oxidation.
 
You may have cooked the coil if you left the ignition on for an extended period of time.
 
Very good possibility. Don't ask me how I know. First, I understand Carpenters coils are crap. Find an original coil and send it to skip Haney for a rebuild. He's the master and his coils will beat anything out there. Around $80.00 including return shipping I think it was the last time I left the key on and fried my coil. Okay, secret's out.
 
couple of pix. I don't think it has an hour of run time.
thanks for the feedback re: Carpenter and the tip about Haney.
it was the Carpenter coil that got hot. the current unit is NOS Motorcraft.
dragged a t-shirt w/ some brake cleaner on it across the points and came out clean. I'll try some 2000 wet / dry.
as a note, I'm used to seeing .016 for a gap. these are set to .012
 

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The points are not set to a specific gap, but are set to achieve firstly a dwell angle for one set of points and then a combined dwell across the two sets.
Mart.
 
MY 1948 8N tractor has a distributor like a 59A crab. I have cooked the coil too by leaving the switch on. I'm done it twice in 30 years. I always shut the fuel off and let it run until it runs out of gas. If you walk away and it runs out of gas, and you forget to go back and turn the ignition off it can fry the coil if it happens to stop in a spot when the points are closed. The windings in the coil are really small and are not designed for constant current flow. The wire has a chance to cool every time the points open

It's either the coil, the points, condensor no voltage to it or its not rotating. It sounds silly but it's always a good idea to crank it and watch it spin first. Maybe not so much on the front drive distributor like a flathead but i have had regular distributors shear the roll pin that holds on the drive gear or the teeth were completely worn away.


So that you don't waste money by guessing, it really helps to have a voltmeter to make sure you have the correct available voltage to it. You can check the resistance of the coil and the continuity through the primary circuit. Check the point gap and make sure they are clean. Go buy a voltmeter, it will pay for itself again and again.

What Mart said is true about setting the dwell but my dad never had a dwell meter and just feeler gauges and an emergency points file, You can get it pretty close with feeler gauges. They say points wear about .001 gap for every 1000 miles driven. As the point gap changes it changes the timing. Dwell effects timing but timing does not effect dwell. If the points are opening and closing you might not have the proper dwell but you should have some kind of spark.
 
Last edited:
Jake's 40 said:
couple of pix. I don't think it has an hour of run time.
thanks for the feedback re: Carpenter and the tip about Haney.
it was the Carpenter coil that got hot. the current unit is NOS Motorcraft.
dragged a t-shirt w/ some brake cleaner on it across the points and came out clean. I'll try some 2000 wet / dry.
as a note, I'm used to seeing .016 for a gap. these are set to .012
Click to expand...
489683


489684
 
@Mart the for the clarification.
@Flathead Fever yes, I have a VOM. I'm getting 5 1/2 VDC to the coil. what should the resistance readings be ?
@petehoovie your message was blank (?)

currently the points have been cleaned & the dizzy reinstalled.
still no spark.

I'm done for the day.
thanks again to all.
 
Jake's 40 said:
@Mart the for the clarification.
@Flathead Fever yes, I have a VOM. I'm getting 5 1/2 VDC to the coil. what should the resistance readings be ?
@petehoovie your message was blank (?)

currently the points have been cleaned & the dizzy reinstalled.
still no spark.

I'm done for the day.
thanks again to all.
Click to expand...


I had to go back and add "bad condenser" to my reply above. I was outside watering, and I thought, crap I forgot to include the condenser too.

I don't know what the resistance is on Early Ford coils but I'm sure someone here will tell us. It's different on each coil type depending on the number of turns in the windings. You can at least check to see if there is at continuity through it. It may or may not have continuity depending on how the wiring melted (if it did melt). At work anytime something like this failed we cut it apart with a hacksaw to see what happened inside. Since these early Ford coils are rebuildable I wouldn't do that.

5 1/2 volts might be a little high on a 6V system with an ignition resistor. That resister keeps the voltage low so the coil does not overheat the windings. MY flathead "projects" are all 12V so I have not played with 6 volt stuff, except on my tractor and that was years ago.
 
Did you check the points for make/break activity when off the car? Put paper between one set of points and connect across the other set and check for continuity. There should be 8 on off events per rev. Move the paper and check the other set.

Once you have cast iron evidence that the points are ok then move on to other things.
 
Lawson Cox said:
Very good possibility. Don't ask me how I know. First, I understand Carpenters coils are crap. Find an original coil and send it to skip Haney for a rebuild. He's the master and his coils will beat anything out there. Around $80.00 including return shipping I think it was the last time I left the key on and fried my coil. Okay, secret's out.
Click to expand...


Lawson,Coils are now $100 + sh. Having one done right now.Just letting you know so his phone doesn't blow up.
 
I agree with Mart. It seems like a lot of folks like to look at the coil as the problem when there is no spark, as the primary cause. In my findings on old Ford tractors mostly, the problem will more often than not, be the points, in some fashion or other. Watch that ammeter/voltmeter when cranking. If the meter is pulsating slightly while cranking, the points are working properly. If there is no pulsation, the points (or something closely related such as the voltage supply wire to the points) are likely the suspect issue.

Al Hook
 
Als48 said:
I agree with Mart. It seems like a lot of folks like to look at the coil as the problem when there is no spark, as the primary cause. In my findings on old Ford tractors mostly, the problem will more often than not, be the points, in some fashion or other. Watch that ammeter/voltmeter when cranking. If the meter is pulsating slightly while cranking, the points are working properly. If there is no pulsation, the points (or something closely related such as the voltage supply wire to the points) are likely the suspect issue.

Al Hook
Click to expand...

That is a great idea! Why didn't I think of that. I've done this for over 40-year's and I still learn something new everyday. Unfortunately, I now forget more everyday than I learn.
 
Jake I would think 5.5 volts at the coil would be too much. I thought it should be closer to 4.5 volts with the use of the resistor under the dash. But if you get a coil from Skip make sure to ask what voltage he recommends. Get a new condenser too.
 
all;
earlier in the week I dug my coil adapter out of storage and swapped it in.
still no go.
today a buddy who is more methodical than I am gave me a hand.
the coil adapter had 2 issues. the high tension coil wire was bad. easy fix but not enough. this "can" coil is a conventional neg. ground unit and I didn't give it it's own isolated mounting. Mr. DuctTape to the rescue.
she fires up.
points are fine.
NOS MotorCraft coil turns to be MotorCRAP.
it's off to Sir Haney for a redo.

@danliveshere yes, agreed. resistor was bypassed. this may have been left over from the emergency use of the coil adapter once upon a time.

thanks again to all.
 
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