mighty demon 650
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mighty demon 650

  1. #1
    Senior Member nos1967's Avatar
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    Default mighty demon 650

    Looking to get a good out of the box carb for my mild 327 sbc jet boat, is the mighty demon 650 mechanical secondaries a good carb? I have a 750 eddy now and hate it, cant handle the 9psi that my fuel pump delivers and it has a bad hesitation when the secondaries open.

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    Quote Originally Posted by nos1967 View Post
    Looking to get a good out of the box carb for my mild 327 sbc jet boat, is the mighty demon 650 mechanical secondaries a good carb? I have a 750 eddy now and hate it, cant handle the 9psi that my fuel pump delivers and it has a bad hesitation when the secondaries open.
    1st... that psi is way too high...should be 6-7psi


    2nd...i would try a Edel 600/625 or a 500 (if u
    can find 1)

    3rd...dont spend the $$$ on a new one...u can
    find small cfm carbs on EBay all day long
    for dirt cheap! ...i have a ton of them

    4th...dont overlook the vac sec carbs!

    this is MHO & my .02 cents

    FastRat
    Last edited by FastRat; 09-14-2008 at 01:43 AM.

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    Senior Member cave's Avatar
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    I have a Demon 850 on the Kachina and if I had it all to do over there would be a Holly sitting on top. Whole lot easier to tune. Once the Demon is tuned its a great carb.

    I had to replace the floats in the Demon. If I turned to sharp the engine would studder. Circle track floats worked good.

    Parts for the Demon like main body parts were tough for me to get. I stripped my front inlet on the bowl and the bowl was a pain to replace. So I ended up JB welding it lol. Parts for Holly are available everywhere.

    I heard that Eddies are easy to tune. But I'm not a carb guy. That's my .0005¢
    Good Luck
    Takin it home

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    Senior Member ol guy's Avatar
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    Quote Originally Posted by nos1967 View Post
    Looking to get a good out of the box carb for my mild 327 sbc jet boat, is the mighty demon 650 mechanical secondaries a good carb? I have a 750 eddy now and hate it, cant handle the 9psi that my fuel pump delivers and it has a bad hesitation when the secondaries open.
    Hey NOS. I have a holley 650 vac secondary spread-bore on the shelf list R 84024 with a flame arrestor. 200.00 ? It cam of my relatively stock 454 jet and worked great just to small. M

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    Quote Originally Posted by ol guy View Post
    Hey NOS. I have a holley 650 vac secondary spread-bore on the shelf list R 84024 with a flame arrestor. 200.00 ? It cam of my relatively stock 454 jet and worked great just to small. M
    he has a 327, not a 454! & spread bore carbs "are" junk...a really good tuned Edelbrock 600/625 or a Holley 600 DP would work great! ...just MHO

    FastRat

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    Senior Member nos1967's Avatar
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    I found a refurbished one for a good price, only reason i was specifically asking about the mighty demon. edlebrock in my opinion doesnt compare to most other carbs out right now, and on a jet boat i really dont see a need for vacuum secondaries...ive used both and will never use vacuum again, at least not on a jet boat.

    cave...i had a demon circle track 650 on my dodge charger and it kicked ass, it replaced a rebuilt holley 650dp and the difference was amazing. I understand where your coming from with the price though, i remember how butt hurt i was when i learned how much i had to pay to get a line kit made at earls but this one came with a line kit so hopefully i wont be spending anymore money on demon in a while.
    Last edited by nos1967; 09-14-2008 at 09:22 AM.

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    Senior Member ol guy's Avatar
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    Quote Originally Posted by FastRat View Post
    he has a 327, not a 454! & spread bore carbs "are" junk...a really good tuned Edelbrock 600/625 or a Holley 600 DP would work great! ...just MHO

    FastRat
    Hey Rat, I realize what size motor he has and thats why I pulled it off my 454. Yeah Im not a big fan of spreadbores either but it came on the boat and I was surprised how well it worked for a pile of junk. Just trying to help out. M

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    Senior Member jetboatperformance's Avatar
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    NOS ,check out Quick fuel tech , wonderfull people nice product ,they've been building custom carbs for us at "shelf prices" call or email if I can help Tom
    http://www.quickfueltechnology.com/


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    Just move the accelerator pump lever to a lower hole. That will give it a bigger squirt when the secondaries open and get rid of the flat/lean spot.
    Takes like ten seconds to do.

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    Quote Originally Posted by nos1967 View Post
    Looking to get a good out of the box carb for my mild 327 sbc jet boat, is the mighty demon 650 mechanical secondaries a good carb? I have a 750 eddy now and hate it, cant handle the 9psi that my fuel pump delivers and it has a bad hesitation when the secondaries open.
    Yep, fuel pressure too high first off.
    I put 9psi against my Holley without problems, but only at 5,000RPM or more (mech fuel pump).
    Any lower RPM and it is lower, 4.5 at idle.

    Hesitation when the seccondaries open is a sign that the6y are opening to soon, a BAD hesitation means WAY too soon. This is adjustable, but I have done Holley vac-secs, no experience with the Ed.

    DuaneHTP on here has a lot of experience with "out of the box" demons and the part-throttle mixture dist. problems they have, on an 8-sensored setup he uses to dyno with. Personally I wouldn't touch one.

    "Out of the box", I don't think you can go much better than a Holley. They won't likely be absolutely perfect, btu they will most likely run great and show no major bad habits.
    "As democracy is perfected, the office of president represents, more and more closely, the inner soul of the people. On some great and glorious day the plain folks of the land will reach their heart's desire at last and the White House will be adorned by a downright moron."
    H.L. Mencken

    OBAMA: Some people deserve this.
    The rest of us are being dragged along kicking and screaming.

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    jetboataholic HawaiianJet's Avatar
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    Quote Originally Posted by jetboatperformance View Post
    NOS ,check out Quick fuel tech , wonderfull people nice product ,they've been building custom carbs for us at "shelf prices" call or email if I can help Tom
    http://www.quickfueltechnology.com/

    And they're made right here in Kentucky (Bowling Green)!!!! I've heard lots of good things about them, and they will probably be my next carb.

    Tom, is that the gas one that you had them anodize blue to look like an alcohol carb?

    HJ

    ***FOR SALE*** 1978 19' Full Stringer Hawaiian Molokai Jet Boat w/ Berkeley 12JC-AB and Chevy 440 Tall Deck ***FOR SALE***

    Quote Originally Posted by mako shark mark View Post
    Oh yeah, Forgot to mention that the hull is a special mixture of speedcote, herculiner and rain-x, all blended together- good for another 8 mph top end.

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    Senior Member jetboatperformance's Avatar
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    Good eye Patrick ,the nice folks there at Quick fuel made that one for me (with the Blue) cause I want to match up all the blue and bling shizzle on my cruiser

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