69 Heat Riser Install Questions - NCRS Discussion Boards

69 Heat Riser Install Questions

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  • Michael C.
    Very Frequent User
    • January 9, 2013
    • 332

    69 Heat Riser Install Questions

    I'm attempting to reinstall the heat riser on my BB after purchasing a replacement flange donut (Fel-Pro) from a local parts store. Using the same studs that I removed months ago I don't get enough exposed threads to attach the nuts. Unfortunately I discarded the old donut so I can't compare the thickness of the old with the new. My first though was that the new donut is too thick. It's listed as 5/8" (.625") thick but actually measures .662". Seems like that's not enough to cause my issue if the original was 5/8".

    Can anyone tell me what the thickness of the donut should be?

    Should the studs be tightly seated into the exhaust manifold? I don't see any information in the AIM or service manual regarding stud tightness. I did back the studs out a couple of threads, but still not enough to get the nuts attached properly. Of course I don't want to back the studs out too far.

    Any suggestions.

    Thanks
    Mike
  • Mark E.
    Extremely Frequent Poster
    • April 1, 1993
    • 4542

    #2
    Re: 69 Heat Riser Install Questions

    Are you sure you're using the same studs? Studs for the RH manifold are longer than the LH because of the heat riser.

    Also, if the studs came out, consider installing new ones. They become brittle with heat cycles and corrosion, then snap the next time you do this.

    And yes, the studs should be fully threaded into the manifold.
    Mark Edmondson
    Dallas, Texas
    Texas Chapter

    1970 Coupe, Donnybrooke Green, Light Saddle LS5 M20 A31 C60 G81 N37 N40 UA6 U79
    1993 Coupe, 40th Anniversary, 6-speed, PEG 1, FX3, CD, Bronze Top

    Comment

    • Michael C.
      Very Frequent User
      • January 9, 2013
      • 332

      #3

      Comment

      • Mark E.
        Extremely Frequent Poster
        • April 1, 1993
        • 4542

        #4
        Re: 69 Heat Riser Install Questions

        If judging points are not a concern, consider stainless steel hardware with high-temp anti-seize.
        You'll thank me later.
        Mark Edmondson
        Dallas, Texas
        Texas Chapter

        1970 Coupe, Donnybrooke Green, Light Saddle LS5 M20 A31 C60 G81 N37 N40 UA6 U79
        1993 Coupe, 40th Anniversary, 6-speed, PEG 1, FX3, CD, Bronze Top

        Comment

        • Joe L.
          Beyond Control Poster
          • February 1, 1988
          • 43221

          #5
          Re: 69 Heat Riser Install Questions

          Originally posted by Michael Carl (57885)
          I'm attempting to reinstall the heat riser on my BB after purchasing a replacement flange donut (Fel-Pro) from a local parts store. Using the same studs that I removed months ago I don't get enough exposed threads to attach the nuts. Unfortunately I discarded the old donut so I can't compare the thickness of the old with the new. My first though was that the new donut is too thick. It's listed as 5/8" (.625") thick but actually measures .662". Seems like that's not enough to cause my issue if the original was 5/8".

          Can anyone tell me what the thickness of the donut should be?

          Should the studs be tightly seated into the exhaust manifold? I don't see any information in the AIM or service manual regarding stud tightness. I did back the studs out a couple of threads, but still not enough to get the nuts attached properly. Of course I don't want to back the studs out too far.

          Any suggestions.

          Thanks
          Mike
          Mike------

          The original exhaust pipe packing was, nominally, 5/8" in thickness. The difference you measure is insignificant.

          The right side studs should be 3-1/6" in length.

          As Mark mentions, I recommend only stainless steel studs for this application. They are available in original configuration.
          In Appreciation of John Hinckley

          Comment

          • Michael C.
            Very Frequent User
            • January 9, 2013
            • 332

            #6
            Re: 69 Heat Riser Install Questions

            I found some studs of the appropriate lengths at a local parts house I can use temporarily until I can get the ss version. They fit fine.
            Thanks folks

            Comment

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