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Tips

no fire from my coil?

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G

gcan

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what makes the coil spark?

I tried to crank my 74B over the weekend with no luck, it was running a week ago. I am not getting a spark from my recently purchased sport coil. I checked the wires going to the coil and have 11 on the positive white wire and 2.2 on the negative white black wire. I even put my old, working, coil back on and no spark. The only thing I have done recently is change some bulbs on the gauges and check the gap on the points. The points were fine so did not have to adjust. The rotor button appears to only go on one way and I checked to be sure it is on good also. I tried the orginal coil wire as well.
I have checked all I know to check and am looking for any advise as to what to check next.

Thank you in advance
Greg
 
Check the points again. Clean them, they might have some film on them and make sure the gap is right. Also check the condenser if the point cleaning doesn't work.
 
The coil is basically an iron core transformer. !2 volts is applied from the switch to the positive terminal (W). The negative terminal (WB) is switched to ground by the points when they are closed.

When the points are CLOSED, the coil carries current in it's primary winding & builds up a magnetic field.

When the points OPEN, the circuit is interrupted, the magnetic field collapses, & a spark is generated by the high voltage winding.

A simple test would be to remove the distributor cap & slip a piece of paper between the points or just open them with an insulated stick. Measure the voltage from coil negative (WB) wire to ground. With the points open or insulated this voltage should be about 12.5 volts or battery voltage. With the points closed & no insulators between them, you should read zero volts from coil negative to ground.

If your reading of 2.2 volts on the negative wire is with the points closed, when it should be zero, there is a loose connection or the points are not making good contact. The small flexible ground wire from the points to distributor housing may not be making good contact, or the points may be dirty.Dirty points is the most likely problem.

If the reading of 2.2 volts is with the points open or an insulator between them, (it should read 12.5 volts) the points are partially grounded, something is shorted, or the condenser is bad.
D
 
I ran the test listed in Dougs attachment and still no fire from the coil.
The sport coil shows 2.3 when tested across the positive and negative and 8.73 when I put the red lead of the meter in the plug outlet and touch the black lead to the negative side of the coil. The coil seems to test good.
I took the points out and filed them flat -
Rechecked the wires going to the coil still 10.73, battery is getting low, amd 2.2 on the negative side.
I checked the wire going into the dizzy with the red meter lead in the connection and the black grounded shows 11.23.
 
sorry ran out of post....still no spark from the coil

how can I have power in and out of the coil yet will not spark?
what should I try next?
 
Did you try another coil? A new coil can go bad as well as an old one. It's worth a try.
 
I did - I have the old one I pulled, which was working, and it also does not fire. I even tried the old dizzy wire.

I feel I have ruled out the coil being bad, the points, the electrical connections, and the wire.

I am running out of things to try

Greg
 
Hi Greg, i feel your frustration. /ubbthreads/images/graemlins/grin.gif Lets try a couple of things: First disconnect the distributor from the coil- at the coil. Switch on the ignition and measure the voltage from the open terminal on the coil to ground it should be about battery voltage. With the volt meter still in place block the points open with a business card. Now just briefly and repeatedly touch the disconnected wire from the coil to its terminal and tell me what the voltage does.---Keoke
 
If you have 12 volts going to the coil, then the only thing I can think of, is there is a short in the distributor. That can be checked with a simple ohm meter. PJ
 
Keoke -
1) with the switch on and the lead disconnected the terminal reads 10.80 (I think my battery is getting weak)

2) with the probe on the terminal on the dizzy and the switch on then when I touch the lead to the terminal reads 0.28

I can also hear the fuel pump change tones everytime I touch the lead.

What does this test tell me?

Thank you for your help
Greg
 
Sorry, I've been gone for the holidays.

Check the voltage directly across the battery terminals. If you've got 10.8v there, don't waste more time on this until you've either recharged the battery or replaced it. A sound, well charged battery will typically be sitting idle at about 12.5v.

Did you completely remove the dizzy from the mix? Hook a test plug up directly to the (Coil's) high-tension terminal and make sure the plug is grounded. Disconnect the low-tension wire between the dizzy and the coil. With the ignition on, tap a jumper wire between the dizzy coil terminal (coil (-) on negative ground cars) and chassis ground. If the coil is good you should see a spark on the test plug.

EDIT: The test plug should be hooked to the coil's high-tension terminal.
 
/ubbthreads/images/graemlins/iagree.gif For the moment with DK, at that voltage the battery is either totally discharged or it is toast. However, recharge it or replace and leave the test setup as it is. I will monitor your progress when full power is restored. Presently the test results seems to indicate we have a short someplace---Keoke
 
I just got home and checked the battery it is reading 11.95, it is less than a month old but is down from trying to chank the B.
 
OK lets go back and repeat the flik test at this 11.95 Volt level. However, this time we are also going to look for a rather bright spark coming off the coil's terminal. Let me know how it goes---Keoke
 
I connected a plug to the coil wire and disconnected the wire to the dizzy then with the ignition on grounded the negative wire off the coil and DID have a blue spark at the plug. I assume this verifies the coil is good.

I also checked the white/blk stripe wire going to the tach and it is clean and has a good connection.

I am charging my battery now it get it back up over 12V.

Now I assume the problem is with the dizzy, and ideas? What could have happened to it? It sat up for 2 weeks and now no fire. I removed the points this morning and filed them down flat to be sure they are clean, regapped to .15...nothing

Help
Greg
 
I want to shift gears just a bit while the battery is charging. What is the highest Ohm Range on your meter and is it an analog type.--Keoke
 
alright now your going to make me feel bad - the only meter I have is a radioShack pocket size meter. The OHM settings are 200, 2K, 20K, 200K, and 2M.

by the way thanks for walking me through this....I'm learning
 
Ok With the power off place the business card between the points. Ground one side of the meter and set it to the 2M range. Take the wire going to the Dizzy and hold the other meter lead on it very firmly. Keep your eye on the meter at all times and tell me what it does.---Keoke
 
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