Author Topic: plug wires  (Read 3877 times)

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390owner

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Re: plug wires
« Reply #15 on: January 11, 2025, 06:24:06 PM »
Still has the miss at a hard pull. New plugs, wires, rotor, and cap. The engine is grounded to the frame and the radiator support and battery. What else could this be?

Thumperbird

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Re: plug wires
« Reply #16 on: January 12, 2025, 07:58:44 AM »
Coil?

CaptCobrajet

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Re: plug wires
« Reply #17 on: January 12, 2025, 01:36:34 PM »
Might be a burnt valve if it only does it under load.  Easy test…….Get it to operating temp, and shut it down.  Take the coil wire off so it won’t start up.  Spin it over and pay close attention to the sound.  Does it skip or speed up as it makes a round or do all of the cylinders sound consistent?  If you have a skip, then check cranking compression to see which one.  If it isn’t up top, it is probably an exhaust valve leaking.
Blair Patrick

My427stang

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Re: plug wires
« Reply #18 on: January 15, 2025, 12:42:57 PM »
If you haven't found anything, consider trying it with vac advance unhooked.  I have seen Ford distributors with bad wiring make and break contact or short as the vacuum advance comes in.  Unhooking it, usually runs ok, then see what's going on. 
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390owner

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Re: plug wires
« Reply #19 on: January 15, 2025, 07:51:59 PM »
I ordered a coil but have not received it yet. Good Idea to try if coil does not work

galaxiex

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Re: plug wires
« Reply #20 on: January 15, 2025, 09:11:22 PM »
If you haven't found anything, consider trying it with vac advance unhooked.  I have seen Ford distributors with bad wiring make and break contact or short as the vacuum advance comes in.  Unhooking it, usually runs ok, then see what's going on. 

This ^^^ was VERY common on the GM HEI in the late 70's early to mid 80's.
GM used rather stiff and "not" very flexible wire on the module in the dist.

I didn't think it was very common on Fords... at least I never encountered it.
Not saying it couldn't happen, just not common.


GM got smarter and started using much better quality, high strand count flexible wire at some point.
Every 20 minute job is 1 broken bolt away from becoming a 3 day ordeal.

shady

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Re: plug wires
« Reply #21 on: January 16, 2025, 09:24:48 AM »
Most fords use a resistor wire from the ignition switch to the positive side of the coil that I've had go bad. Make sure that you have the proper voltage on the coil. Also make sure the coil isn't connected backwards ( - side goes to the points). Lastly don't overlook a bad ignition switch. You can always hot wire 12v to the + side of the coil and see if that fixes the miss, but it will be hard on the points so you might want to put an old set in to try.
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390owner

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Re: plug wires
« Reply #22 on: January 20, 2025, 08:25:09 AM »
Replaced the coil did not make any difference. I have a hei dist.  so no points Thanks for all the replies