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Spark plugs....

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by ol_grayfeather, Jul 8, 2002.

  1. ol_grayfeather

    ol_grayfeather Registered Member

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    Its time to change my plugs again and I'm thinking of trying a different kind. I currently use AC Delco R45TS gapped at .045, I think. The motor I run is stock except for a Edelbrock intake and carb. The color of the plugs now is black, carbon and oil I'm guessing, not the tan color i've heard they're supposed to be. So basically I'm wondering if I should go to a hotter plug or maybe even a different kind all together. The distributor and coil are just stock HEI and I've got store brand wires.

    Thanks

    Dan
     
  2. ol_grayfeather

    ol_grayfeather Registered Member

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    BTW its a 350 in a 3/4 ton truck that is in 2500-3000 rpm range most of the time.

    Thanks,

    Dan
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    If I'm not mistaken, thats the correct heat range for most SBC 350's, so I'm not sure whats going on. You could try shortening the gap a bit, I *thought* Chev went up to .045 for like one year, then went back to .035.

    FWIW, running my plugs at .050, I've not noticed any difference in idle quality, mileage, driveability, anything.
     
  4. xnoahx

    xnoahx 1/2 ton status

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    You could try upgrading the coil and module in the HEI to get a more powerful spark. The coil is simple to replace and is only about $40
     
  5. ol_grayfeather

    ol_grayfeather Registered Member

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    What would one hotter step up be? Brand and numbers...

    Thanks
    Dan
     
  6. TopOff

    TopOff 1/2 ton status

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    If you go to a hotter plug, most likely you will get spark knock without knowing it and could put holes in your pistons.

    I would check your ignition timing, and check your carb jets/ choke.

    If it is a higher mileage engine, and your experiencing spark plug fouling, get some Champion plugs. Champion's are a softer metal and these plugs tend to run cleaner and foul less. The downside is they don't last as long.

    Good luck.
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Sorry I really don't know. On all my motors (up until now) I had been running the $.99 autolites. Since my last bout with them (2 of 8 brand new failing in 40 minutes) I will be going with Delco's from here on out.

    I really don't think a hotter plug is the answer, unless I'm mistaken, thats for cases where you NEED a hotter spark, like high compression engines, nitrous, etc. Stock didn't need hotter plugs, you shouldn't either is what it comes down to.

    Closing the gap will help keep plugs from getting fouled the way I see it, as the spark has an easier time jumping the shorter gap, and thus, more reliable ignition to keep the crud from building up (coked oil)

    HEI has no problem jumping 1/2"+, but combine that with trying to do so under pressure, and with oil thrown in, and its not easy.
     

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