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Ignition Problem... I See Sparks!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by SAVAGE1, Nov 2, 2002.

  1. SAVAGE1

    SAVAGE1 1/2 ton status

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    Okay, I've managed to stump every car guy in town. When I put in my new crate motor in back in March, I used the basic Accel wires and AC Delco plugs. Everything ran fine until I was getting some misfires in the ignition. I narrowed it down to one of the plug wires being smashed against the firewall and the insulation was wearing down. I replaced the wires with MSD 8.5mm Super Conductors. I only changed the wires and left the same plugs in. I took it for a drive and everything ran great, actually ran better than before. After about 10 mins on the way home it began to misfire. This time it was worse than the original problem. It would even die sometimes at idle. I then put new plugs in and nothing changed. I ran the motor in the dark and I can see sparks "glowing" under the spark plug boot. Its not an actual arc jumping, all I see is a slight glow coming from under the boot. I followed the directions on crimping the MSD wire connectors so I don't know what's going on. A spark means a bad connection but I don't know what I did wrong. /forums/images/graemlins/1zhelp.gif
     
  2. chillywilly

    chillywilly Registered Member

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    Ive seen something like this before on newer trucks.Once the spark arcs the side of the plug itll leave whats called a carbon track.Pull that plug and look for a small grey line that u cant rub off with fingernail.Probly b a matching line inside of boot.Most likely you will have to replace plug and wire on that cylinder.Oh dont forget to put some silicone grease on the new ones..prevents arcing.Good luck!!! /forums/images/graemlins/cool.gif
     
  3. sosamantx

    sosamantx 1/2 ton status

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    hmmm, i'd maybe check the resistance of the wires themselves and see what that tells you? what did the plugs look like when you took them out, cap and rotor etc.? ignition problems can be a pain in the butt sometimes, but you need to do the basic checks. i'd check the cap and rotor as you didn't mention them. i've actually taken my wizard (dremel tool) with a small wire wheel and cleaned off all of the corrosion build up off of my cap and rotor. as for the sparks i don't know? maybe what chillywilly said?
     
  4. HarryH3

    HarryH3 1 ton status Author

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    Did you put any silicone dielectric grease on the inside of the boots before you installed them? If not, then you can have a problem with the spark sneaking past the boot. Get a tube of the grease and smear it around the inside of the spark plug boots with a Q-tip. That should solve the problem. /forums/images/graemlins/cool.gif
     
  5. SAVAGE1

    SAVAGE1 1/2 ton status

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    Thanks for the responses guys. I went ahead and bought some cheapo $20 wires to put in place of the MSD's. The truck ran fine. I will try to install the MSD wires with dielectric grease to see if that's the problem. I'm just glad I narrowed the problem down to the wires.

    Thanks again.
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    My plugs (cheapy autolites) have a dull glow to them as well at night, I chalked it up to light (spark) transmission through the ceramic.

    No idea for certain thats what I'm seeing, but I don't have any "misfires" because of it.
     

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