Keep fouling number 3 and 8 plugs - NCRS Discussion Boards

Keep fouling number 3 and 8 plugs

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  • Joe L.
    Beyond Control Poster
    • February 1, 1988
    • 43211

    #16
    Re: Keep fouling number 3 and 8 plugs

    Originally posted by Lawrence Shaw (22476)
    Thanks guys I really appreciate the feedback. I have AC 44XLS plugs in the engine now. So I will change out the plugs in number 3 and 8 cylinders to AC 5. I am guessing this is the heat range 5 we have been discussing. I don't see where I can buy a 45XLS at Napa, Advance or Autozone. They just have the "5".

    Lawrence
    Lawrence------


    I believe the "5" the parts store is probably referring to is one of the AC Rapid Fire plugs. You want the AC R45XLS. Most parts stores will carry this. I don't think you'll find 45XLS anywhere today.

    If you replace the valve seals, I would seriously consider replacing the valve springs at the same time IF they're original springs. If you find valve springs with an outer spring and inner damper, these are most likely the original springs of GM #3859911. You DEFINITELY want to replace these. If you find springs with an inner and outer spring configuration, then your springs have already been replaced. In that case, definitely keep using these springs. The GM inner/outer spring assembly is discontinued.

    If you do replace the valve springs, use Sealed Power VS 1581. This is an outer spring/inner damper but it's not prone to breakage like the original GM #3859911.

    While the GM valve spring assembly is discontinued, the retainer (cap) with integral seal is still available. However, I don't know, for sure, if these can be used with the VS 1581. I don't think they are compatible but I could be wrong. Anyway, if you have the updated, dual spring, these are the ones to use. These are GM #3964264. The problem is they GM list for 15 bucks each and you need 16 of them.

    If you use the Sealed Power valve springs (i.e. outer spring with inner damper) you should use the stock-type (for your 1967 original application) UMBRELLA seals. The GM seals are discontinued. However, I'd highly recommend using Victor-Reinz B45296 or Fel-Pro SS71152. These are premium FLUROELASTOMER seals. These will probably outlive you. You WILL find that if you still have your original springs and valve seals, the valve seals will be TOTALLY DETERIORATED.
    In Appreciation of John Hinckley

    Comment

    • Gene M.
      Extremely Frequent Poster
      • April 1, 1985
      • 4232

      #17
      Re: Keep fouling number 3 and 8 plugs

      The issue is oil in the cylinder. Bad seals or guides. Fix that. Playing around with different plugs does not fix the problem.

      Comment

      • Michael H.
        Expired
        • January 29, 2008
        • 7477

        #18
        Re: Keep fouling number 3 and 8 plugs

        Originally posted by Gene Manno (8571)
        The issue is oil in the cylinder. Bad seals or guides. Fix that. Playing around with different plugs does not fix the problem.
        Yup, a hotter spark plug is just a bandaid that will only slightly prolong it's untimely demise.

        When big blocks run for a long time huffing oil, they usually wind up with broken top rings.

        Comment

        • Lawrence S.
          Very Frequent User
          • April 1, 1993
          • 800

          #19
          Re: Keep fouling number 3 and 8 plugs

          I agree it is a band aid. I will replace the guides or seals, but in the short term I need to run the right plugs.

          I was looking at the plugs in my 69 stock Z/28 and they are 45's. I now know why they don't foul out.

          I will keep you guys posted on my next steps.

          Thanks again.

          Lawrence

          Comment

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