No spark

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doc308
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No spark

#1

Post by doc308 » Sun Aug 09, 2009 12:54 am

I've completed my '50 bobber and just began to wire the ignition up. Using a test light with the ignition switch turned on, the light lights up at the positive side of the coil, the ignition switch, and the battery, as it should. However, when I kick her over to test for spark there is none AND the coil becomes very warm-almost hot. I switched out the coil for another one I had lying around and the same thing happened. So, juice is getting from the battery to the ignition switch and from the switch to the coil, but there is no spark and this heating thing happens. I do have the other post of the coil wired to the distributer, as it's supposed to be. I switched the wires to the opposite posts on the coil, with no luck. What's going on?



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Re: No spark

#2

Post by john HD » Sun Aug 09, 2009 1:31 am

points not opening?

john

doc308
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Re: No spark

#3

Post by doc308 » Sun Aug 09, 2009 1:56 am

They seem to be opening. I installed new points when the engine was on the bench. Maybe I should double check the gap.

Another q--I noticed that in testing with the light , the post on the coil which the distributer wire is attached to is not a hot wire--ie the the light doesn't light up . I think that this is normal because the other post is hot (?)

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Re: No spark

#4

Post by FlatHeadSix » Sun Aug 09, 2009 2:04 am

doc
I think John might have your answer but it may not be the points, you might also have a short in the wire coming from the timer.

Disconnect the wire coming from the timer at the coil, turn on the ignition and see if the coil still heats up. If not you need to start checking the wire from the timer with your ohm meter. The points supply ground to the coil when they are closed, when the points are open you should have no resistance between the end of that wire and chassis ground. So, bump the engine over until the points open and sheck to see if the timer wire is still grounded, if it is then you need to start checking to see if the points or condenser are installed correctly and not shorted to ground.

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Re: No spark

#5

Post by FlatHeadSix » Sun Aug 09, 2009 2:18 am

you are correct doc, your light should not work when connected to the timer side of the coil. As I said above, the positive side of the coil should read battery voltage with the ignition switch on (your test light will light), the other terminal is the negative terminal and receives its ground when the points close and complete the circuit. That's why the timer is also called a circuit breaker, every time the points open it breaks the circuit to the primary winding in the coil and it goes dead until the points close again and complete the circuit. Both plugs should fire every time the points open.

A quick check for your coil would be to connect one of your plug wires to a loose spark plug and lay it on the head or anyplace where it will be grounded. If you have the timer wire disconnected from the coil you can use a jumper wire from the negative battery terminal or anywhere else on the chassis. turn on the ignition and "flash" your ground jumper to the negative coil terminal, the plug should spark every time you flash the wire against the coil connection.

mike

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Re: No spark

#6

Post by doc308 » Sun Aug 09, 2009 2:37 am

Thanks very much for the tips, John and Mike. I'll do a check on these things tomorrow and give you some feedback. So, it sounds like the problem of the coil heating up is likely in the timer circuit.

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Re: No spark

#7

Post by doc308 » Tue Aug 11, 2009 2:42 am

Problem solved. You were right, the wire from the coil to the distributer was flawed. I replaced it and things started sparking. Thanks so much for the guidance--you were right on.

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