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COLD, COLD, COLD, and fouling sparkplugs

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Slayer, Mar 7, 2002.

  1. Slayer

    Slayer 1/2 ton status

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    <font color=blue>Got a question for the technical experts.
    </font color=blue><font color=red>
    I installed a 383 stroker motor (GMPP), Holley 750cfm 4-barrel, Holley fuel pump, DynoMax headers, MSD ignition, 8.8mm plug wires and a 5inch K&amp;N air filter.

    The motor ran fantastic all of last year, up until January of this year, when the temps were dipping into the minus digits.

    Then the motor started fouling spark plugs, mainly because it would only run with the choke out (manual choke).

    My guess is that the K&amp;N lets air into the intake too fast, without warming up at all, which causes the motor to run lean, wanting the enriching choke.

    I tried a paper air filter, thinking that it might be more restrictive, yet no luck.
    </font color=red><font color=green>
    Actually thinking about going back to the stock air filter box, with the warm air inlets that come off the exhaust.
    Also thinking about covering part of the front grill, with something better than cardboard.

    Any suggestions?? And yes, I run the cheap AC Delco plugs, and I tried going 1, 2 and even 3 steps hotter, still no luck.
    </font color=green>
     
  2. muddin4fun

    muddin4fun 3/4 ton status

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    What kind of adjustments have you made on the carb?


    No matter how long you let it warm up, it needs the choke?

    If it's taking a long time to warm up, you might also look at the cooling system...like if it's opening up too soon. Also, do you have a clutch fan or something like a flex fan that spins all the time?
     
  3. Slayer

    Slayer 1/2 ton status

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    Running a 190 degree thermostat.

    Yup, running a flexifan and it spins ALL the time. Possibly switch to electric fans with an inside-cab control..........

    Carb was adjusted as best as the local racing guru could get it. Ran GREAT all year, just started having trouble this winter.

    Yup, no matter how long it warms up, or drives, it still requires the choke out.
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Perhaps your thermostat has failed, and is stuck open? I had a car that the PO had removed the t-stat (I thought the gauge was wrong lol) and although it worked fine, it was running at about 100 degrees all the time. (yes, tested with kitchen thermometer, and I could hold my finger in the coolant after driving for 30 minutes) It would NEVER heat up, no matter how hard I drove it. Didn't foul plugs, ran really strong, but very rich because of another problem. Bosch plugs never gave me problems.
     
  5. CaptCrunch

    CaptCrunch 1/2 ton status

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    Have you tried re-tuning the holley in? Holleys are a constant maintance and tune carb. Weather changes can effect them. I always had to retune when the weather got cold when I was running my old Duster 340 in Fargo. I would retune in the carb myself... of course with the choke on all the time you are gonna foul out plugs. Get the motor up to temp and try retuning in. If you have a problem with temps then look at thermo stat, fan or possible just a cover for the frt radiator opening. My truck warms up much better with my cover on in the winter
     

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