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Old 05-21-2019, 11:20 PM   #1
justanotherguy
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Default SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

Hi. I looked but couldn’t find my exact problem on previous posts… close but not exact. I don’t post much, because I don’t know much. I’ve said this before - I come here to learn. You all seem to have the brains I need right now. I’m hoping I missed something painfully obvious. Here’s the back-story, which might offer clues in this trouble-shooting puzzle:

My 59AB is 12-volt neg ground with a front mount FOMCO crab distributor converted to single points. The car actually ran better than one would think, considering compression was really low on 3 cylinders. But I decided a rebuild was in order, and took the stripped down engine to a machine shop familiar with flatheads. Engine comes back, all seems right. Time to reinstall everything. Oil pressure up. # 1 cylinder now at TDC on compression stroke. Let’s begin.

A new 12-volt coil (with built in resistor) was installed along with a new condenser. Since the points have less than 20 miles on them and look like they just came out of a box, I decided to clean them (didn’t really need it) and set the gap (.015).
Rotor and cap also less than 20 miles, look brand new, were cleaned, and coil terminal in cap lightly sanded to insure clean contact. Inside of cap is spotless.
A new set of plugs and wires were installed. Plugs were gapped to .028. It may not matter, but I’ll point out that the wiring harness on this car is practically new and the car lives in a dry, vermin free, garage, and has for over 15 years.

Good strong battery, with heavy 2 gage pos and 1 gage gnd. Ignition on, engine turns smoothly and rapidly, but no spark.
Test coil: Good spark at end of lead to distributor. This is gratifying.
Test coil with ohmmeter anyway. It falls within manufacture’s specs.
Check points again. They seat flat and have held the gap during several attempts to start. (Remember this car ran fine before on “single points”.)
With distributor in place, I turn on ignition and separate points with screwdriver to hopefully see spark. No spark at points.
Not likely but maybe garage lights are too bright. I turn off most lights.
Ignition on. Repeat points and screwdriver. No change.
With most lights off, test at plug (#5) by positioning plug wire ¼” from plug terminal. Ignition on, crank starter. No spark.
I double-check that all plug wires and leads are firmly set (actually triple check).
Ignition on. Repeat plug test. No spark.
Condenser lead is not touching anything it shouldn’t… besides it’s neg ground so, shouldn’t matter anyway.
Test neg lead from coil to distributor by switching with new wire I know is good. Ignition on. No change. Not surprising, since previous wire was also good.
(At his point, I’ll try anything.)
Even though it shouldn’t matter, I remove distributor-to-block gasket just to be sure distributor is grounded well. Ignition on. Try again. No change.
Swap out new condenser for another new in box (Borg Warner).
Ignition on. Try again. No change.
Replace distributor with my back-up FOMOCO distributor that is running stock 2 points configuration. Clean points, check gap.
With back-up distributer in place, I turn on ignition and separate points with screwdriver to hopefully see spark. No spark at points.
Reinstall my single point distributor and check points and gaps again.
Get third condenser. Ignition on. No change.

Perhaps it’s time for a beer. I rarely drink beer.

I have now displayed all of my knowledge on troubleshooting an ignition system. Truthfully, everything I tried (mentioned above) has always worked on any other car that I’ve had in the past. So I’m out of ideas. This is where you, my friends that I only call on when I need something, come in.

Any help or earnest feedback, opinions, etc. is welcome.
THANK YOU!
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Old 05-22-2019, 01:44 AM   #2
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Default Re: SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

so whats the problem dont over think it if you have spark at the high tension lead to the cap your low side is working fine the fact that you cant see a spark at the points means that you have a match between your coil and condenser .Remember its that spark at your points that actually burns them [like a very small arc welder ] and the condenser actually absorbs that spark [ take the condenser out and see how long they last and how much of an arc you get at the points ]
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Old 05-22-2019, 01:56 AM   #3
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Default Re: SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

sorry only read half of your post so you have spark at the coil and i assume its strong and regular as you didnt say otherwise it either has to be grounding within the cap or rotor or you may have a broken lead between the coil and cap
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Old 05-22-2019, 02:06 AM   #4
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Question Re: SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

just a quick thought you say the new coil has a built in resistor you did remove the built in resistor under the dash in the ignition circuit as two resistors will cut back your feed voltage to your coil dramatically [may not even have 6 volts to the points ]
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Old 05-22-2019, 03:20 AM   #5
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Default Re: SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

rotor or cap is bad; your coil is producing spark, but it's not getting to plugs. Try another rotor, then another cap
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Old 05-22-2019, 06:59 AM   #6
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Default Re: SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

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59ab dist. have a screw in post that the wire from your coil should be attached to. That post has a spring loaded contact which presses against the point plate inside your dist. Try unscrewing that post and running a wire direct to the points and you should have a circuit. The plug the hole around the wire with silicone sealer.
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Old 05-22-2019, 01:06 PM   #7
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Default Re: SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

Just curious. How do you convert a crab distributor to single points, and why? I wonder if that .015 gap on single points will give you sufficient dwell to build up the coil voltage for a big spark. I guess that depends on the shape of the cam in that distributor.

Check the little protruding thingie at the center inside of the distributor cap. I had one go missing on a Mallory distributor and the spark could not make the leap from the coil wire to the rotor.
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Old 05-22-2019, 02:43 PM   #8
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Default Re: SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

Hi Guys. Thanks for all this good feedback.
Aussie Merc - the blast resistor under the dash has been bypassed. I should have mentioned that... but that was a good thought.
Brian - I have switched out cap and rotor sets. I have even mixed up cap and rotor sets. I have adjusted spring tension on the rotors. I have lightly sanded (very fine sand paper) coil contact inside caps. I have cleaned inside of terminals. I have switched back and forth to my dual points distributor.
(Drolston - to convert to single points you remove the dwell set of points and re gap primary points to a slightly larger gap and they work... but you're right, I don't really see the advantage either. It was set up that way before. Regardless, I'm not getting spark with either set up)
JimTN, I'm going to try your idea tonight or tomorrow when I can get back to it (other obligations in my "normal" life, go figure) ... your suggestion is one thing I haven't done yet. Thanks again, everyone!
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Old 05-22-2019, 03:20 PM   #9
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Default Re: SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

I had the same thing happen to me that MR DROLSTON spoke about. Mine was corroded and the contact spring and needed to be cleaned off.
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Old 05-22-2019, 04:10 PM   #10
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Default Re: SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

You said that the secondary side of the coil is firing at the distributor end of the coil wire. That indicates that the circuit from the coil distributor terminal and the points is working. The points and condenser have to be working for the coil to fire. I can only surmise that the problem is between the end of your coil wire and the rotor getting the spark to the cap terminal. You say you have changed all the parts including trying another distributor. Was the spare distributor known good, or has it been sitting around for a while?
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Old 05-22-2019, 04:27 PM   #11
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Default Re: SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

How about the plug wire that goes from the coil to the distributor cap?Maybe there is a bad connection or wire there.
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Old 05-22-2019, 04:54 PM   #12
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Default Re: SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

Didn’t leave out the rotor button I hope!!!!
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Old 05-22-2019, 08:58 PM   #13
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Default Re: SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

I had a Corvair once the had a hairline crack in the coil tower. I worked good most of the time, but if it got a little moist out, the spark would take the path of least resistance and fire through the crack to ground instead of going to the distributor. It was a bear to track down.
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Old 05-22-2019, 11:44 PM   #14
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Default Re: SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

lots of good suggestions so far ,Not sure if this will help but more on the low tension side . (single point ) pull the small coil wire from the distributer fit a test light or a bulb between it and the distributer terminal key on ,crank the motor bulb should go of and on as the points open and close ,if it stays on you have a grounded points or condenser or terminal ,if it goes on /off ,reconnect the small wire n Pull the HT lead wire from the distributor and hold it 1/4 from the head should jump a spark ,wriggle a screw driver between the points should throw a spark from the HT wire if it does you may have fauly points.,
pull the condenser wire,tie the condenser wire to the small coil wire and ground it of/on should throw a spark from the coil ,if it does you may have faulty points .
Dble points
most times one point will be closed so no screw driver test would work you need to put some card between one set ,And as above you may need to look at the Rotor and cap ,
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Old 05-29-2019, 08:22 PM   #15
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Default Re: SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

Well, here's brief update, but still no spark.
I walked away from this to attend to other things and figured it would be good to have a break anyway.
Don, leaving the rotor out is something that I could certainly do, but that's not the case.
34pickup, I did swap that out with a different lead, but it provides a strong spark just like the original.
jimTN, I did a variation on your suggestion... I removed the primary terminal base and terminal looked clean with no corrosion on terminal or on points plate. I lightly sanded anyway and reassembled making sure there was solid contact.
What else... With my multimeter, I double checked voltage coming from ignition to coil and I'm getting 12.+ volts. All contacts are clean.
FlatheadTED, now unless I misunderstood your suggestion/instruction, possibly something else is going on. I hooked up a 12v test light to the distributor primary wire and and it never lit up. (clue?) I also bypassed the primary wire and hooked the test light directly to the coil and still no light. It's good light, as it works on the battery just fine. Remember this primary terminal "sparks" the secondary wire fine, when scratching against a grounded surface.
There are a few more things on my list to check and I'll update again when I know more. I suspect I've forgotten to put the rotor in.
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Old 05-29-2019, 10:59 PM   #16
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Default Re: SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

You say you have 12 volts coming in to the coil ?and you have spark at the secondary /HT wire ?, so if the test light is grounded and the other end is touching the coil terminal/ (primary ) with the wire removed it should light up ,on of as you crank it ,
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Old 05-31-2019, 12:33 AM   #17
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Default Re: SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

I HAVE SPARK AT THE PLUGS.

I just typed a very long story as to what happened and it was deleted when I tried to post.
Rats.

So here's the short story: The top insulated terminal inside the distributor was cracked. I made a 1/4" x 1 5/8" brass strip to connect both sides and it works. Probably a temporary fix, but it worked. Thanks to everyone for guiding me along. Tune in next time when I try to put gas in the tank.
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Old 05-31-2019, 01:53 AM   #18
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Default Re: SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

Stuff happens.
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Old 05-31-2019, 09:27 AM   #19
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Default Re: SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

Thanks for posting the solution to the problem. It may help someone else in the future.
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Old 05-31-2019, 10:17 AM   #20
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Default Re: SPARK at COIL but NOT at POINTS - PLUGS, seeking advice.

I'd post some photos but the service I used a long time ago now wants money, and I don't use it that much. What's a good (free?) way to post photos?
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