Mighty Demon 850 Needle/seat issues

Discussion in 'Holley' started by DasRottweiler, May 29, 2020.

  1. DasRottweiler

    DasRottweiler -BuickAddict-

    Secondary bowl keeps flooding. Started at hard stops , then turns , then as soon as electric fuel pump kicked in at startup. Fuel blowing right thru needle/seat. Has been an issue before, time to order new needle/seats.
    I ordered 110 viton needle /seats with springs for heavy duty and marine applications.
    The needle/seat I removed was a self contained unit, that is, you can pull it out, drop it back in. However, the new ones came in pieces, as seen in pic.
    What the hell am I supposed to do, pull the carb , flip it upside down to install these?
    2020-05-29 18.40.24.jpg
  2. Bens99gtp

    Bens99gtp Well-Known Member

    Pull the bowels,you might be able to use some vaseline to stick it all together and the gas will dissolve it away
    DasRottweiler likes this.
  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Pull the bowls and invert them.
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  4. DasRottweiler

    DasRottweiler -BuickAddict-

    That thought came to mind after typing "pull the carb, flip it upside down".
    I bought a palm ratchet for removing secondary float bowl screws when rejetting carb, guess I'll put it to use tomorrow morning . Thanks for the replies gents! As long as I didn't get a "toss em , they're garbage." I'll move forward....Jim
  5. telriv

    telriv Founders Club Member

    See that o-ring on the old needle & set??? MANY times it's that o-ring. Try changing it BEFORE replacing. IF you have any old Holley or Demon rebuild kits usually there are extra o-rings in the kit that VERY OFTEN don't get used.

    Tom T.
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  6. DasRottweiler

    DasRottweiler -BuickAddict-

    I do have a used rebuild kit, I'll check for o-rings. Ty for the tip......Jim
  7. DasRottweiler

    DasRottweiler -BuickAddict-

    Pulled the o-ring off the original needle/seat. It was brittle and snapped while being removed. The culprit , no doubt. I got my o-ring assortment out and matched it up, installed needle/seat assembly , reset float level and bumped the electric fuel pump , and wella , she holds!
    Thanks for your replies gents, and Tom T, thank you for the tip, proved most helpful!
  8. telriv

    telriv Founders Club Member

    Glad I was able to help Jim.
    Hopefully you didn't use any old o-ring from an assortment. It NEEDS to be fuel compliant that's why I mentioned a rebuild kit as the o-rings in them are fuel tolerant.

    Tom T.
  9. DasRottweiler

    DasRottweiler -BuickAddict-

    I did find a couple in the rebuild kit I have. That fuel compliance thing crossed my mind....Thanks again.

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