No fire from coil part 2

Keeper79

Keeper79

Member
OK been several days since last on, been waiting on replacment parts.

3rd coil arrived along with a new condensor. Didn't install the new condensor and I am still trying to get fire from the coil.

Hooked up the new coil, turned on the power to the car and checked the voltage at the points. With the points opened I have just over 6 volts, (6.05) and with them closed I have nothing (0.00)

held the coil wire about 1/16 or so to a head bolt and opened the point several times and nothing. No spark jumping. :(

Have done some reading over the past several days about bench testing the coil. Using a voltmeter you can test the primary windings and the secondary windings. doing this you need to know the resistance specs for the coil. Anyone happen to know these?

Figure I have 3 coils so far that haven't given me a spark. Might as well test this also, and be somewhat productive.

kinda at a loss right now of whatelse might be causing me to get no fire.

Thanks again for any help.

Dave
 
Per Steve Pargeter at the recent NWRG seminar on ignition, etc. he says the primary resistance should be 2-3 ohms and the secondary should be 8 ohms. However, I believe he is wrong on the secondary--it should be 8000 ohms from everything I have read and a couple of knowledgeable electrical engineers who were at the seminar. I personally haven't tested a coil since the seminar, but given the sources, am confident that the 8000 ohms is correct.
 
My notes show
1.2 Ohms primary and 3,200-4,400 Ohms secondary

I think the difference is because one is 12 volt coil and the other is 6 volt I don't have in the notes which one is the 4000 Ohms.
 
Your voltages are correct. As soon as the points open the high voltage should travel the coil wire and spark to ground. Are the metal end tips soldered?
 
The rotor and cam on the distributor do rotate just fine. Have watched this several times and the points are opening and closing nicely.

I agree 3 bad coils in a row does seem odd, but then again I have crappy luck sometimes and have learned to just let it go. (think its pay back from my youth) :eek:

I haven't tried another coil wire yet. Have checked it several times and the continuity on it great and resistance is great. Did try a larger wire 8 gauge wire I believe a few weeks ago when I first found the coil not firing. Folded up one end to stick into the coil and the other end near a bolt head and still nothing.

What end tips should be soldered? On the coil wire? Will have to look at them again. I looked at them last night when I checked the continuity again and the wire looks great as it was brand new.

Thanks again for the help guys.. I had hopes of having this car running over a month ago for my mother in laws birthday. Hope they could have went out onto town in the A, but it will be great its all fixed in running.

Dave
 
when your points open and close with the key on do you see a little spark at the point contacts?

make sure your coil wire is good. you can even stick a screwdriver in the coil in place of the coil wire and hold it close to a ground and see if that sparks...

take a test light put the alligator clip on a head nut and make sure you have power at the coil black wire.. then while cranking the testlight should flash at the coil on the red wire with the opening and closing of the points. when testing this at the coil make sure you right on the threaded coil posts to eliminate a break in the wire connectors
 
This isn't making any sense. If you have 6 volts at the points with the contacts open, and 0 volts with the points contacts closed, that means the points are working and well grounded. You tried a #8 wire, and still had no spark. If the condenser is good, that only leaves the coil. Just hard to believe 3 bad coils.

One more check you must make. With the key on and points closed, check the voltage at each of the two coil primary terminals and let us know what you have. I have another thought on the problem, but want to know the results of this check first.
 
Tom Wesenberg said:
This isn't making any sense. If you have 6 volts at the points with the contacts open, and 0 volts with the points contacts closed, that means the points are working and well grounded. You tried a #8 wire, and still had no spark. If the condenser is good, that only leaves the coil. Just hard to believe 3 bad coils.

One more check you must make. With the key on and points closed, check the voltage at each of the two coil primary terminals and let us know what you have. I have another thought on the problem, but want to know the results of this check first.
Click to expand...


i am with you tom

i hope he didnt set the point per my previous screw up lol
 
I haven't see a spark at the points when they break contact, I have cleaned up the contacts on them.

I did check the coil posts last night to make sure I still had power at the coil. I can't remember which post had what, but do recall the voltage. One side was reading 6.04 and the other had a 5.88. Again I can't recall which side had what. This was with the ignition switch on, and the points closed.

maybe 4th coil is a charm? or just put a modern MSD ignition system under the hood. :) j/k

Dave
 
That's exactly the answer I was looking for. Either your distributor isn't properly grounded, or the contacts are dirty or burned, or the ignition switch is bad, or the wires running to the points. Remember, you have the short flexible wire inside the distributor.

One of the primary terminals should be showing 0 volts, or very close it it, but since it's showing 5.88 volts only a small amount of current is finding it's way to ground, which is through the ignition switch, wire to points, points, and distributor (which should be touching ground).

Now, check the voltage on each of the switch terminals. If you have a repro switch, it may be making poor contact, as mine did. You just have to keep checking voltage to find out where the bad connection is.
 
Oh boy..

well the ignition switch was an issue I solved for right now. The switch wasn't great and the contact of it was sketchy when turned on.. Need to order a new one or fix and rebuild this one. I did bypass the switch with a toggle switch, this was a quick and easy way to help problem solve and elimiate things.

So.. Now I get to dig a little deeper into the wiring and find out why I am grounding out part of the way.

Thanks for the help.. will see about working on that this evening.

Dave
 
If you have 2 problems in the same circuit at the same time, that's when it can really be puzzling to find the problem. Bypassing the switch was good, so if you now show 5.88 volts on both switch terminals, with the switch on and points closed, that would indicate the problem is further down the line towards the points. The points showed 0 volts, so that should mean they are well grounded, so the problem should be further up the line towards the coil. A likely suspect might be the short flexible wire between the upper and lower distributor plates. If that wire is good, then it could be a bad connection where the ignition cable screws into the distributor and the brass contact touches the buss bar on the bottom plate. If that is a clean good connection, then I'd look for a bad wire in the ignition cable. The point is to keep going along the circuit to find out where the voltage reading isn't what it should be. You know we're working on the points side of the coil primary circuit, and this side is the ground side of the primary circuit, so everything should read 0 or close to 0, allowing for a very small line loss.

What is the wire you are using to run into the distributor? If it's an original popout cable, then it may be time to replace the wire inside the steel cable.
 
The line going into the distributor from the ignition was replaced. The original one was actually bent a little bit in the tunnel under the dash/cowl/fuel tank. The armored piece was removed and from distributor and the wire pulled out.

The button on the distrib side cleaned up and put the spring and plastic piece back in. Feed wire through armored cable back into firewall and up in the tunnel to the switch. The end going to the distributor was put back in only tightened down finger tight.

Dave
 
Just to make sure the points are well grounded you could use a jumper wire from the upper plate arm to ground. The hole in the head is usually a good source for ground, but if it's full of rust, don't count on getting a good ground there.
 
OK got a few questions after looking into a few things last night. Think electrical trouble shooting is just a few steps worse than smacking your thumb with a hammer.

Points are grounded, replaced the wire from the lower and upper plate last night just because the old one was origional and sorta rough looking.

Was thinking about the coil having power on both sides and trouble shooting back from it. the positive ground still gives me some trouble in my thinking. Is the positive or negative side suppose to have power all the time, and which side is suppose to not have it? Might help me trace some wires back.

Don't know if this helps or not, just checking stuff with my brother in law who stopped by. The wires coming from the generator and the starter go up into the box. He checked continuity from both on the posts where the wires connect to both sides of the coil and the meter chimmed up. He was wondering if one of them could be grounding out and causing the issue.

Thanks again for any help..

Dave
 
If you have an owner's manual look at the wiring diagram. The coil is always "hot", and gets it's ground when the key is turned on and connects the ground side of the coil (+) to the points. So, when the key is off, or the points are open no current flows and both sides of the coil will show 6 volts, as well as the wire leading to the ignition switch. Once the circuit is completed the current will flow, and the 6 volts will be dropped through the coil primary windings, so now one side of the coil should show 0, or close to it, allowing for a small line loss.

Did you use the correct very fine stranded flexible wire inside the distributor? It should have at least 100 strands of fine wire. Ordinary primary stranded wire will break from the flexing that takes place when adjusting the spark advance.

Mike V. has also often posted a very good wiring diagram.
 
Her you go;

Wiring-DiagramColor2sm.jpg
 
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