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Discussion Starter #1
I put the 250 L6 from my 71 into a 73 just for fun. The 250 only has 64,000 original miles on it.

Now I've transplanted it. It started perfectly on the very first try....but then never again. I checked everything....I found it had no spark....I had 12 volts at the coil so I figured coil was bad. I bought a new coil...hooked it up...started perfectly...purrrrred like a kitten. Ran it a few times, then just now while letting it run in the garage...it just shut off. Now it won't start.

Same thing no spark!

What can kill the coil? I don't have the wiper/pump motor installed in the firewall so all of those associated wires are currently un-connected..do any of those have anything to do with the coil? I think plugs and wires are original, but it starts and runs fine when things are working...

Any ideas?
 

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Ignition coils are hard to kill and most times a diagnoisis of a bad one is incorrect. It is just a mini transformer, has 2 seperate windings that induce voltage from one to the other. The amount of windings determine the voltage. It is filled with oil to help cool the windings. If you have a point type distributor the + side of the coil should only be fed about 9 volts to keep from burning the points contacts prematurely. The - side is the ground through the points and the dwell, amount of time points are closed, will determine the saturation and ultimatly the voltage of the spark when the points open and the coil discharges to ground at the spark plug. Check out the condensor that is tied into the contact points in the distributor, if it shorts to ground it will cause a no spark condition.
 

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Discussion Starter #3
Philip said:
Ignition coils are hard to kill .....Check out the condensor that is tied into the contact points in the distributor, if it shorts to ground it will cause a no spark condition.
Thanks Philip, I'm not very familiar with points systems, I'll see if I can figure out what the condensor is under the cap.
 

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A little siver can about an inch long and 1/2" dia. It has a wire that attaches to the contact point terminal. It is mounted to the base plate with one screw. Be careful not to drop the screw!!
 

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Discussion Starter #5
Philip said:
A little siver can about an inch long and 1/2" dia. It has a wire that attaches to the contact point terminal. It is mounted to the base plate with one screw. Be careful not to drop the screw!!
thanks Phillip!! I'll check it out.
 

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If you are using older used coils they can leak out their oil and die pretty quickly. New one isn't real expensive and may be an option for you.
 

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Philip said:
...It is just a mini transformer, has 2 seperate windings that induce voltage from one to the other...
It's actually wound as an autotransformer, which means that it is a tapped single winding.
 

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Discussion Starter #8
Real McCoy said:
If you are using older used coils they can leak out their oil and die pretty quickly. New one isn't real expensive and may be an option for you.
The second one was a brand new replacement from the parts store. I'm getting the idea that it is a pretty simple device and it would be hard to destroy a new one just running the engine a few times.

The other detail is when I had the engine out, I pressure washed it with the distributor in place. I suppose I could have moisture inside the distrbutor cap, but then why would it run fine with the new coil for a while, then suddenly quit?

Is moisture in the distributor a likely cause of this problem? Or would moisture make it not run at all?
 

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Discussion Starter #9
Problem solved.

After almost pulling my hair out of my head chasing ghost shorts ( i would undo a screw and the lights would come on!), I tested the voltage from the positive battery bost to the ground on the engine for the 100th time....but this time...nothing! I followed the negative battery cable right to the battery where I realized I never tightened it down last time I took the cable off.

Tightened the negative battery terminal...and wola! problem solved.

Lesson: Every electrical gremlin I've ever had has turned out to be something VERY simple. I kept saying this over and over in my head all afternoon today...but I STILL failed to check the simplest thing..be sure my battery cables were tight.

Thanks to all those who tried to help.
 
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