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Fix Motor Mount
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Ford 6R80 6 spd
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Points style ignition, No spark from coil...
- Thread starter reamer
- Start date
Broncobowsher
Total hack
- Joined
- Jun 4, 2002
- Messages
- 35,043
Probably not. Remember how points work. They open and close the ground. The coil gets 12V (through a ballast resistor that drops it to about 8V under load) from the ignition. The coil ground is switched by the points in the distributor.
Take your meter (or a test light even) and check the negative side of the coil again. Put a ratchet on the front of the crankshaft and turn the engine slowly while watching the meter/light. At some point, should be less than 1/4 turn of the crank, the meter will read almost no voltage or the test light will go out. At this point the positive side of the coil will drop to about 8V due to the ballast resistor. That is if everything is working.
Now you have shown you have the 12V to the coil, and through the coil. But you have not shown if the points are working. If the above test never makes a complete ground, you are getting closer to your problem. And it probably isn't the coil. When was the last time you changed/adjusted the points? It is a service item. You can also get corrosion buildup on the points and they can physically close but not conduct electricity.
So a really short answer to your question, no you have not confirmed anything is wrong with the coil. So far it appears to be working correctly with what little testing you have done.
Take your meter (or a test light even) and check the negative side of the coil again. Put a ratchet on the front of the crankshaft and turn the engine slowly while watching the meter/light. At some point, should be less than 1/4 turn of the crank, the meter will read almost no voltage or the test light will go out. At this point the positive side of the coil will drop to about 8V due to the ballast resistor. That is if everything is working.
Now you have shown you have the 12V to the coil, and through the coil. But you have not shown if the points are working. If the above test never makes a complete ground, you are getting closer to your problem. And it probably isn't the coil. When was the last time you changed/adjusted the points? It is a service item. You can also get corrosion buildup on the points and they can physically close but not conduct electricity.
So a really short answer to your question, no you have not confirmed anything is wrong with the coil. So far it appears to be working correctly with what little testing you have done.
OP
OP
- Joined
- Mar 20, 2008
- Messages
- 1,249
Cool, I have removed the coil and did a Ohms test both high and low pass, points (haven't played with them for over 20 years) But to my defense I just got this Bronco Thursday, Went through and ran a thin sheet of emery cloth to both sides of the points and now have a have a spark at the points and #1 plug!
But must of stressed the crap out of the starter and the relay. The batt terminals were getting very hot and a little "smokey" Thinking the inards of the starter are now shorting, the truck has been sitting dead for almost 20 year, and this is the first time in decades to attempt to start it.
But must of stressed the crap out of the starter and the relay. The batt terminals were getting very hot and a little "smokey" Thinking the inards of the starter are now shorting, the truck has been sitting dead for almost 20 year, and this is the first time in decades to attempt to start it.
- Joined
- Nov 3, 2003
- Messages
- 47,854
That can be due to bad connections at the cables, bad cables themselves, a tired starter, or an engine that's hard to turn over. All easy to test.
Before you replace the starter relay though, make darn sure it's bad, because chances are pretty high that the new one will be worse!
Unless you pay a high price for a USA made one, it's a crap shoot.
But check your cable connections, to make sure they're clean and tight. Disconnect them from their relative positions and clean any rust, paint or other blockage and re-attach.
If they are old, or worse yet, original(!) then just replace them with some 4 gauge, or better yet 2ga cables all the way around.
Make sure that the ground cable is attached directly to the engine block, and NOT an appendage somewhere else. The closer to the starter motor even, the better.
Make sure there is still a ground to the body. If the original cables have been replaced at least once, this is often overlooked by the installer.
Turn the motor over by hand like Broncobowsher was saying. Even if you are no longer testing the ignition, try to turn it over by hand to see if it's tight. This puts lots of strain on the starter.
If the engine is pretty grimy, I would even remove the distributor and clean the shank where it enters the block, and make sure that bore is clean too. This is overkill in most cases, but with a new-to-you but ancient rig, who knows how well things are connected.
Since the whole ignition relies on the good ground connection between the distributor body and the engine block, it's just good to know how clean it is.
Wasn't an issue 40 years ago, but now that these things are all closing in on 50 years old, these little things can make a difference.
And the next time you have it cranking you should have a timing light connected so you can verify the ignition timing is not too high. That will put strain on the starter as well.
Good luck.
Paul
Before you replace the starter relay though, make darn sure it's bad, because chances are pretty high that the new one will be worse!
Unless you pay a high price for a USA made one, it's a crap shoot.
But check your cable connections, to make sure they're clean and tight. Disconnect them from their relative positions and clean any rust, paint or other blockage and re-attach.
If they are old, or worse yet, original(!) then just replace them with some 4 gauge, or better yet 2ga cables all the way around.
Make sure that the ground cable is attached directly to the engine block, and NOT an appendage somewhere else. The closer to the starter motor even, the better.
Make sure there is still a ground to the body. If the original cables have been replaced at least once, this is often overlooked by the installer.
Turn the motor over by hand like Broncobowsher was saying. Even if you are no longer testing the ignition, try to turn it over by hand to see if it's tight. This puts lots of strain on the starter.
If the engine is pretty grimy, I would even remove the distributor and clean the shank where it enters the block, and make sure that bore is clean too. This is overkill in most cases, but with a new-to-you but ancient rig, who knows how well things are connected.
Since the whole ignition relies on the good ground connection between the distributor body and the engine block, it's just good to know how clean it is.
Wasn't an issue 40 years ago, but now that these things are all closing in on 50 years old, these little things can make a difference.
And the next time you have it cranking you should have a timing light connected so you can verify the ignition timing is not too high. That will put strain on the starter as well.
Good luck.
Paul
- Joined
- Apr 21, 2013
- Messages
- 2,840
"Before you replace the starter relay though, make darn sure it's bad, because chances are pretty high that the new one will be worse!
Unless you pay a high price for a USA made one, it's a crap shoot."
+1 on what Paul said!!!
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"With key on, there is 12V on the small coil wire from the dash But there is also 12V on the other small wire"
From that description it sounds as if the points are closed allowing the +12 volts to show up on the other terminal because there is no ground. As the points open the 12 volts saturate the primary side of the coil, when points close they send that voltage to ground. That sudden collapse of voltage on the coils primary winding induces a larger voltage in the coils secondary winding and that runs down spark plug wire and jumps the gap in you spark plug to get to ground.
Good luck!
Unless you pay a high price for a USA made one, it's a crap shoot."
+1 on what Paul said!!!
------------------------------------------------------------------------------------------------
"With key on, there is 12V on the small coil wire from the dash But there is also 12V on the other small wire"
From that description it sounds as if the points are closed allowing the +12 volts to show up on the other terminal because there is no ground. As the points open the 12 volts saturate the primary side of the coil, when points close they send that voltage to ground. That sudden collapse of voltage on the coils primary winding induces a larger voltage in the coils secondary winding and that runs down spark plug wire and jumps the gap in you spark plug to get to ground.
Good luck!
- Joined
- Apr 21, 2013
- Messages
- 2,840
"ran a thin sheet of emery cloth to both sides of the points and now have a have a spark at the points and #1 plug!"
The corrosion between the point contacts was probably your lack of ground, same as opening the points, only they appeared to be closed (grounded).
The corrosion between the point contacts was probably your lack of ground, same as opening the points, only they appeared to be closed (grounded).
- Joined
- Nov 3, 2003
- Messages
- 47,854
Just to add to one thing ared said, the spark event actually happens when the points open.
All the rest is true about saturation and such (though I'm never sure when it's doing what) but the break-down of the field happens when the ground is opened.
So I guess that means that saturation occurs as the current is flowing fully through the thousands of coil windings and out to ground through the points. As soon as the ground is eliminated when the points open, all hell breaks loose in the coil and the sparks fly. Presumably with everything looking for a new path to ground, which ends up being through the spark plugs.
Now, I may have that wrong of course, as I don't know diddly about theory. But I wanted to bring it up because I'm "pretty sure" that the spark happens when the points break open.
I suppose I could have read up on it online first, before posting up and being wrong. But hey, where's the fun in that and it's a good topic of conversation while it's going.;D
Paul
All the rest is true about saturation and such (though I'm never sure when it's doing what) but the break-down of the field happens when the ground is opened.
So I guess that means that saturation occurs as the current is flowing fully through the thousands of coil windings and out to ground through the points. As soon as the ground is eliminated when the points open, all hell breaks loose in the coil and the sparks fly. Presumably with everything looking for a new path to ground, which ends up being through the spark plugs.
Now, I may have that wrong of course, as I don't know diddly about theory. But I wanted to bring it up because I'm "pretty sure" that the spark happens when the points break open.
I suppose I could have read up on it online first, before posting up and being wrong. But hey, where's the fun in that and it's a good topic of conversation while it's going.;D
Paul
- Joined
- Apr 21, 2013
- Messages
- 2,840
You're right, I said that wrong. While the points are closed current is flowing through the primary winding of the coil to ground, once the points open energy is "induced" into the other winding and due to one having many turns and the other having few the induced voltage is much higher than the 12 volts we started with. Like several thousand volts and it wants to get to ground! Even willing to jump a gap at the plugs to get there.
