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Electrical Test Question

May 17 2017 at 5:19 PM
Pootnanny  (Login Pootnanny)


I'm troubleshooting an electrical Gremlin with my MSD ignition box, distributor and coil. My Mustang's FE motor isn't getting spark so I'm doing some testing to determine where my problem is.

After determining that I have power to my MSD 6AL box, I attempted to test the MSD ignition box per mfg. directions. I basically pulled the coil wire off the distributor cap, placed the distributor terminal about 3/16" from a ground, turned the key towards the start position and shorted the 2 green and violet distributor wires to the MSD box with a paper clip. I was unable to get spark between the coil wire and the ground. Per MSD, this test is used to determine if the MSD ignition box is bad.

One thing I wanted to eliminate was a potential bad coil wire interfering with this test. I'm currently using the large Taylor 409 wires. My current coil wire is approximately 10" long.

Can anyone advise if I'm testing the coil wire properly. I set my multimeter at 20K Ohms and took a reading off the coil wire's terminal for the distributor and the terminal for the coil. My multimeter indicated a reading of 0.35 which seems low.

I don't have a current replacement to switch out a coil wire for a test. Electrical is not my strong point but I'm trying to learn. Can anyone advise if there a problem with this wire?

Thanks all who chime in!

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(Login MT63AFX)

Make sure the metal tang on the rotor is bent up enough to contact. .......

May 17 2017, 7:43 PM 

.....the center post, RodC.
Mickey Thompson's 63 1/2 #997 S/S Hi-Rise 427 Lgt/Wgt Galaxie,
1957 C-600 Cab-over carhauler w/390-4V, 2-speed rear-end
FGCofA member #4908
MCGC member #75

"There will ALWAYS be an FE in my LiFE"

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(Login Falcon67)

Who made the wire

May 18 2017, 6:25 AM 

And then look up the spec of ohms per foot for that cable. They are not all the same - sample from Taylor wires:

Q. What should the Ohms per foot be on my wires?
A. ThunderVolt 50 = 40 Ohms
ThunderVolt 8.2 = 40 Ohms
StreeThunder = 500 Ohms
409 Pro Race = 350 Ohms
8mm Spiro Pro = 350 Ohms
8mm Pro Wire Resistor Core = 3,500 Ohms
Full Metal Jacket = 350 Ohms
Extreme Service = 350 Ohms
SST = 500 Ohms
8mm High Energy = 5,000 Ohms

For a 6AL, I'd try the white wire to ground as that is the trigger for use with points. It works separate from the mag pickup wires. Also, an easier test is to hook up another distributor with a mag pickup - like a Duraspark - and just spin it with your fingers. Rig a wire that will fit the coil tower with a plug boot on the other end, stick in a spark plug and lay that on the motor or use a jumper to ground the electrode. Spin and look for spark. No spark, use the white wire and bounce it off clean metal ground and check for spark. Still no spark - unit is likely dead. For a coil, just go get some cheap coil at the parts store.

This message has been edited by Falcon67 on May 18, 2017 6:28 AM

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