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Not getting spark - need some quick help


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Hey guys, I just need some quick help here. I'm probably overlooking something blatantly easy and I'll really appreciate it if you could point anything out. I feel like a lot of us are great with the mechanical aspect of things, but the wiring aspect of things really throws us off.

 

I just dropped my engine into the car and am now trying to get it to run. Have no problems with the fuel side of things, but I can't get any spark to save my life. I have isolated the problem to be before the distributor because I'm not getting any spark from the coil wire to a grounded source when cranking.

 

New NGK plugs gapped at .036", new 7.5mm wires, new cap, new rotor, and I'm on my third coil (first two were rather old and had some corrosion on the body so I didn't really count them for being worth much). The only thing I haven't replaced is the actual wiring itself and the dropping resistor. I have gone through and cleaned all of the contacts with sandpaper or an abrasive pad until they shined.

 

Could an old resistor be the cause of all my issues? I didn't think they went bad

 

I've been pouring over the diagrams in my haynes manual, and they have taught me the basics along with google of how everything works, but I know I don't know enough to get to the roots of my problem.

 

After lots of searching I have found that the most common issues are with bad grounds and the ignitor, but I'm not sure where to go.

 

Thanks in advance guys!

 

 

I've included a pic of how I have everything hooked up as of now.

 

labeledcoil.jpg

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First, be sure the points haven't closed up on you. Next, put a volt meter or test light to the coil + contact with the ignition on. It should read 12V or the lamp should light. If no voltage there then check on either side of the resistor. If voltage is there then try jumping out the resistor to see if you can get voltage to the coil. The resistor is only there to drop the voltage so the points/coil aren't burned up during normal operation. If no voltage on either side of the resistor (with ignition on) then you can run a wire from the B+ of the battery to the + contact on the coil too. That eliminates the harness. It a matter of isolating and this should help get you in the right direction.

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Well, I'm back in town now so I'm able to work on the car a little bit more.

 

I grabbed the voltmeter and with the key in the on position I have my 12volts to the positive terminal on the coil, but I'm still not getting any spark from the coil output wire (to the dizzy) to a known ground that I used to see if I was getting voltage to the coil.

 

Maybe the coil isn't getting the signal that the engine is cranking?

Time to start hunting around with the voltmeter and a schematic...

 

 

edit:

I haven't found out much. All I discovered was a ground that was unhooked. I cleaned it up with sandpaper and screwed it back in, verifying it with a voltmeter. Didn't make any difference. I also verified that my points haven't seized up on me.

 

Any clues?

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*puts on my best hillbilly accent*

 

shoooooot

 

So that's it?

Lets see if she fires up now!

 

edit:

I swapped the wires on the + and - terminals of the coil, but I'm still not getting any spark out of it :(

With the key in the "on" position should I be getting 12volts at all of the wires in my diagram? I have 12volts on both ends of my dropping resistor and at the + and - terminals on the coil when going to a ground.

 

edit2:

I just confirmed that the coil is getting power while cranking as well as in the on position. The voltage drops to ~9.5, but I'm assuming this is just due to the large load of the starter.

Would this point towards a bad coil?

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Check the points. Make sure you've got connectivity from the - of the coil to the points. A magnetic field is induced in the primary windings when the points are closed. When the dizzy rotates and opens the points the field in the coil collapses causing the secondary windings to send high voltage to the rotor/cap/plugs. If the points are actually working (opening/closing) and there connectivity then it might be a bad coil.

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Well, I thought my points were good, but that was before I looked under the cap of a distributor on one of my parts cars! The point were free, but the po had left the cap off for ~14 years so there was some corrosion that wasn't obvious at first to me. Definitely not rust, but just a dull oxidation. As soon as I put the new distributor in I had spark :D

 

Thanks so much for all of your help Mark!

Definitely wouldn't have gotten this without you.

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