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Reading Spark Plugs

Discussion in 'Intermediate CJ-5/6/7/8' started by 3b a runnin, Nov 24, 2020.

  1. 3b a runnin

    3b a runnin Active Member 2023 Sponsor 2022 Sponsor

    I drove my 73 cj5 today to put in my labor for the day. I noticed a fairly severe miss in the 360.
    When I got home, I pulled the plugs to take a look see. 6 out of 8 had large, heavy white carbon deposits. Other 2 had some.
    I'm not very good at this, but what I read, and pics I can find in my old manuals, tell me this is probably poor quality fuel.
    The engine only has approx. 6k on it. It was bored .030, and got an Edlebrock cam, forgot the specs on it, and a Qjet, with a DUI ignition. Plugs are Autolite 65's.
    What do y'all think? Would it help to use a hotter plug?
    [​IMG]
    [​IMG]
    This is 2 different plugs.
    Opinions please:shrug:
     
  2. Lockman

    Lockman OK.....Now I Get It . 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Yes , IMO. And ditch the Autolites :rolleyes:.....cross over to NGK. Best plug made , today. What heat range does the TSM say to use ?
     
    3b a runnin likes this.
  3. 3b a runnin

    3b a runnin Active Member 2023 Sponsor 2022 Sponsor

    Autolite 65 is the basic for a 1980 model 360. They are gapped at .042. Surely something could be better than this.
     
  4. PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    WTF??? In 6k miles???? Something major is going on...

    And I don't think there is such a thing as "white" carbon.

    Are you losing coolant at all?
     
    3b a runnin likes this.
  5. Downs

    Downs Rattlecan All The Things!

    The chart I just looked at mentioned excessive oil as being the reason for ashy deposits like that.
     
    3b a runnin likes this.
  6. PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Well, yeah. Except they don't look "oily."

    Still grossly abnormal. Need to find the source. PCV malfunction?
     
    3b a runnin likes this.
  7. nwedgar

    nwedgar Now with TBI!

    FWIW I use Champion RN12YC (404) in my 360 for the past couple years and have not had any issues. I keep them gapped 35-40, and I have throttle body injection using the Ford large cap distributor with TFI coil.
     
    3b a runnin likes this.
  8. sterlclan

    sterlclan Member 2024 Sponsor 2022 Sponsor

    Ac Delco all the way champions are for lawn mowers and Harley’s.
     
    3b a runnin and Walt Couch like this.
  9. Desert Runner

    Desert Runner Member 2024 Sponsor 2022 Sponsor

    Without trying the start the whole Fram/Champion insanity rage...

    I have used RN12YC for 42 years with no issues. And I run PH11.
    and that's all I'll say about that.
     
    3b a runnin and Rich M. like this.
  10. Walt Couch

    Walt Couch sidehill Cordele, Ga. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    How old is the fuel?
     
    3b a runnin and timgr like this.
  11. mike starck

    mike starck Member

    Can't blame the spark plug regardless of brand.The deposit is the result of excessive oil or coolant or something contaminating the fuel.
     
  12. 3b a runnin

    3b a runnin Active Member 2023 Sponsor 2022 Sponsor

    No loss of coolant at all. It does burn more oil than it should. I expected oil to show up as oily plugs.
     
  13. Downs

    Downs Rattlecan All The Things!

    Screenshot_20201125-194714_Chrome.jpg
     
    3b a runnin likes this.
  14. AKjeff

    AKjeff Member

    Are those the original plugs from the break in, or were they changed?

    Any chance there's assembly lube deposits on them, then coated with ash from combustion?
     
    3b a runnin and Downs like this.
  15. 3b a runnin

    3b a runnin Active Member 2023 Sponsor 2022 Sponsor

    Yes, they are the original plugs. Never been out.
     
    Downs likes this.
  16. 3b a runnin

    3b a runnin Active Member 2023 Sponsor 2022 Sponsor

    What plugs are you guys running in your 360?
     
  17. bigjohn

    bigjohn Active Member

    I still run autolite but mine are gaped to.. 050 with the dui ignition. I burn lots of oil as well buy mine are darker deposits, not ashy like that. That's crazy.
     
    3b a runnin likes this.
  18. Rich M.

    Rich M. Shoe salesman 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Agreed that's a deposit problem. Possibly plugs are not gapped right / cold. I would think by now the rings would be seated. Try a leak down test? Valve guides, stem seals ok?
     
    3b a runnin likes this.
  19. sterlclan

    sterlclan Member 2024 Sponsor 2022 Sponsor

    I run ac r44slx
     
    3b a runnin likes this.
  20. 3b a runnin

    3b a runnin Active Member 2023 Sponsor 2022 Sponsor

    I've ordered a set of AC R45xls. We'll see.
    Thanks Guys