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MSD 6AL spark test, scary results!

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  • MSD 6AL spark test, scary results!

    Dear All. I have a Ford 302 running a MSD 6420 6AL CDI box, with an MSD 8202 Blaster coil, and an MSD 8479 Pro-Billet distributor. The engine has been running fine with this setup for 15+ years. The vehicle has been dry stored for around two years. I've just replaced the plugs, leads, distributor cap & rotor. The interior of the distributor required cleaning due to corrosion.

    I retimed the engine & it starts & runs OK for a short period, but then cuts out. Fuel pressure is good, all wiring & connections have been checked. I check for a spark as per the MSD manual, i.e. remove the plug lead, unplug the green/violet distributor lead & short with a jumper lead. The resulting spark form the coil lead to earth is continuous, & very strong. It looks like a welding arc. The spark continues even after I remove the jumper. I have to kill the ignition to stop the spark.

    I've enclosed a YouTube link sowing the problem. I've enclosed a photo showing how it's wired up. Also, the rev counter is going mad, the needle goes to the max when the engine isn't running & gives erratic readings. Can anyone help please?

  • #2
    Julian. I installed the same ignition setup in my Sunbeam Tiger, a 260 Ford. First the engine would start and run, then quickly die, never to start again. MSD tech line believed it was a defective 6425 so Summit racing sent another one. Same thing happened again! They had me check the manufacture date, 7/22 on both. They thought was a defective batch, so Summit Racing sent a third 6425. In the meantime, I replace the starter solenoid and cleaned up and replaced terminals to ensure ground. All worked as of two days ago.
    You may have a defective 6425 as it sounds like constant spark is a short.
    On the green-purple connector it is NOT permanently jumped for spark test, you simulate a 6425 trigger by quickly shorting-unshorting with the jumper.