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  1. #1
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    Default 83 GT Spark Plug Recommendation

    I am planning to do a compression test on my 83 GT and in the process change plugs. I currently have Motorcraft ASF 42C. Looking at my previous plug change 10 years ago, I had ASF 52C plugs in. I know they are a slightly hotter plug. Is there an advantage to going back to that plug? Its a stock motor with headers and Edelbrock 1406 carb. I checked one current plug (ASF42C) and it was slightly black. Looking at my old plugs (ASF 52C) were nice and brown. I know this could be a tuning issue, but was wondering if a hotter plug would be better. What are the disadvantages of going to a hotter plug?
    Thanks
    83-Steaman

  2. #2
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    Any advise on plugs?
    83-Steaman

  3. #3
    FEP Super Member erratic50's Avatar
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    Default

    If you go too hot on plugs you will end up with pre-ignition. The car will sit there and diesel after you shut it off

  4. #4
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    From a chart I found online, Heat Range of 1-3 is a cold plug, 4-7 is medium and 8-10. Looking on Rock Auto, an 84 GT takes ASF 52C plug which is only one heat range up. A 84 GT has the same set-up as a 83GT. Can anyone confirm ASF 52C plug is used on a 84GT?

  5. #5

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    My manual says that 1982 through 1985 5.0 carbureted uses ASF-42, with a gap of .044, and the 5.0 CFI uses ASF-52, with a gap of .050.
    Last edited by AJ1398; 03-21-2019 at 08:54 PM.

  6. #6
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    Default

    Thanks for all your help guys!!
    83-Steaman

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