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Discussion Starter #1
The car died recently, restarted and drove it home. Now it will turn over and occasionally a cylinder will fire, but the engine will not start. This morning I hooked up my multi-meter to the battery side of the coil and turned on the ignition. I got 5.5 volts with the key in RUN, then disconnected the battery cable to the starter ( so the engine would not turn over), turned the key to start and got 12 volts to the coil. Is this an indication of a bad ignition switch, because I'm pretty sure 12 volts should be going to the coil with the key in RUN? This is a 1964 1/2 170 ci. engine w/automatic transmission. Thanks in advance for any and all ideas or thoughts!
 

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Your readings are a bit low, but about right. You will only read battery voltage at he coil when the points are open. When the points are closed, you should only read half battery voltage, because the circuit is then complete, and half the voltage is dropped by the resister wire. You get full battery voltage in "start" because the wire from the ignition terminal of the start relay bypasses the resister wire for easier starting.
 

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This morning I hooked up my multi-meter to the battery side of the coil and turned on the ignition. I got 5.5 volts with the key in RUN, then disconnected the battery cable to the starter ( so the engine would not turn over), turned the key to start and got 12 volts to the coil.Thanks in advance for any and all ideas or thoughts!
This is normal. Additionally, with the engine running @1500 rpm, you should see about 7V at the coil.
 

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Just curious...what type of ignition system are you running? Just as the previous post said, the ballast resistor (or, if it's still there, your resistance wire) is bypassed at start (so you'll get the full 12 volts), but runs at three to four volts lower than that once you've started. Seven sounds pretty spot on, perhaps a bit on the low side by a volt (again, as the other dude said).

I'm curious what happened after the mentioned "fails to start." Did you get your girl running? I had a similar issue and traced it to a fried ignition module (mallory). They've lowered the price on the replacement modules ( e spark, 6000M, I believe...39.95 at summit last week). I also bought one of their internally resisted coils and ditched the ballast altogether. If that's your system, this might help.....

There are THREE wires coming from the dizzy (I have a unilite). IT IS CRITICAL FOR THE BROWN WIRE TO BE GROUNDED TO THE ENGINE BLOCK. Mine was grounded to the chassis AND the bolt was rusty. The alternator wasn't grounded, nor was the mechanical VR (by definition, I don't believe the mech is normally grounded, but of course I grounded when replacing it with an electronic). Though I've seen much debate regarding where folks like their red wire, directly on the positive of the coil is fine, as is splicing it in pre-ballast resistor. The first way is lower voltage for the module AND coil, the second is just for the coil (unless I haven't had enough coffee yet). The green wire goes on the negative of the coil. As I've seen more times than not here, keeping that coil running where you are now is what's critical (most coils do require a ballast resistor or res. wire), and NOT the ignition module for this particular system. Good luck!
Danielle
 

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Discussion Starter #5
Its the stock ignition system. Today I took a known good spark plug, pulled off the #6 plug wire and connected it to the plug. I firmly rested it on a bare metal engine spot, cranked the engine and got maybe two white arcs across the plug gap and that was it. Tried it a couple more times later with the same results. Bad coil maybe? Rechecked voltage to the coil with the wire disconnected from the coil and got 9 volts. Could the coil be dragging down that voltage? Thanks for all the ideas already!:yup:
 

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When was the last time you did a standard tuneup? New points, check distributor cap for cracks, wear on contacts, rotor button, plugs, wires , timing, condition of wires. I'd start there.
 

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Discussion Starter #8
I did a complete tune a couple months ago. Changed everything from the condenser to the plugs, then set the points with a dwell meter and the timing with a vacuum gage. It ran beautifully. Thanks all!
 

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I suspect your condensor went bad, I always carry a spare in the glove box. If you have your old one and it was running fine before you did the tune up, put it back in and see if the problem is fixed. Condensors can fail at any time, even if they are new. Good Luck.
 

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Hi, I'm having the same type of problem with a 68 shelby gt500' 428
It will run good for about 8miles or so, then it shuts off. If I let it cool off for about 10 minutes, it will start back up.

I think it's the coil. I'm changing it this week and will let you know if it works..

Good luck
Mike. :kooky:
 
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