Demon 750 on a 12 sec 360 jet size?

Fuel and Air Systems

  1. A360

    A360 Benton

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    G/Day fellas

    Just had a 2nd hand Demon 750 given to me to replace my 830 too big annular holley on my 360.
    It is on and running fine but seems to be much too rich ,so I was going down in jet sizes then I had a thought to ask you fellas ,someone would have been there and done that with a similar combo such as I have.I did bollow a holley 750 DP with 80's all round which ran a 12.7@109 at the track but have heard the Demons are not the same hence the question.

    Question is what jet size or range for the following

    750 Might Demon on a
    360
    10.5 CR
    Torker 2 intake
    extractors into 2.5 twin
    727 3000stall
    3.9 gears in a 9''

    1970 Valiant Hardtop (Dodge Dart)
    Have run 12.7 @ 109 with 1.9 60'
    with holley 750DP 80 size jets

    Thanks guys in advance

    Benton

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  2. dgc333

    dgc333 Well-Known Member

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    The 750 Demon is likely going to be too big too. The Demon carbs are wet flow rated and the 750 you have is more like an 800 Holley.

    I tried a 725 Demon on my 360 and could never get it sorted out to run right below 2000 rpm.
     
  3. redfastback

    redfastback Don't ask me... my garage is empty

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    my friend runs that holley 830 on her 360 and runs 11.50's with 12:1 compression. the holley 750 sounds better. i agree with dave, forget the demon.
     
  4. A360

    A360 Benton

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    Dont have much choice due to $$$$$ issue I have the demon but what I have found out so far that I have jet a few sizes below that a holley of the similar size.

    Thanks for the feedback so far

    Benton
     
  5. abodyhotrod

    abodyhotrod Well-Known Member

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    my 750 mighty demon came with 76 83 jets.
    i have a wide band air fuel meter and those jets were to rich at WOT, since found 72 79 works for me in the southwest.

    360 .30 over stock build
    low compression
    mild cam 480 480
    eddy heads
    high rise
    tti's 3in x pipes
    4.11 3800 stall
    daily driver

    no 1/4 times
     
  6. doug 371

    doug 371 Well-Known Member

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    love that car! :)
     
  7. A360

    A360 Benton

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    Finally checked the jet sizes yesterday.
    77 front 89 rear

    Dont know what this was running on before but certainly does not suit my application.

    Trying 73 front then using the 77's for the rear as a base to work from.

    Then tune up or down.

    Benton
     
  8. 388dart

    388dart Well-Known Member

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    You are on the right track now - maybe 72/80s - it is a 750dp Speed demon?
    maybe try #35 squirters too. make sure fuel is level in the centre of the windows.
     
  9. A360

    A360 Benton

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    G/Day Fellas

    just an update on the 750 demon and the tuning of it to suit my 360.

    After trying a variety of jet sizes I have ended up with the fllowing;

    Front jets 80
    Rear jets 81

    the thing is flying now and puling right through to redline in each gear except top (keep running out of road)

    So it only took me a few months ,admittedly on and off to get to this point.

    But it is running hard now

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  10. SRT_DSTR15

    SRT_DSTR15 Well-Known Member

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    so what are the new times?
     
  11. A360

    A360 Benton

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    Not at my track untill later this month. (Winter Break)

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