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Thread: Tearing my hair out over this one!!!!! any ideas??

  1. #1
    Senior Member EXPERT BUILDER
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    Tearing my hair out over this one!!!!! any ideas??

    O.k. I have a 377 ci stroker 400 block 350 rotator crower cam#00350,iron bowtie angleplug heads holley strip dominator intake, hooker supercomp fenderwell headers,th350 with shift kit and a coverter seems to be about 3-3200,4;10 gears 28 inch tall tire, 2990# with me in itand i have been havin carb issues ,yes the infamous bog @ 2k, hit it twice and she goes,everyone screams lean,but i kept going up with everything in my 4779 holley 750,finally after bout givin up i installed a 650 #4777 I had here, and Holy S#@%,this thing is flying now,but I only had it on the street for short rips ,but I am blown away ,is this carb correct for this setup??,I put it on to try it and this set up likes it,thanks for any input

  2. #2
    Administrator RACING JUNKIE bjuice's Avatar
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    i would say your in the ball park if it picked up that much ( you knew this one already lol ).

    i assume your valves are 2.02 or 2.05...any major head work ?..any port work to intake...and last what size cam are you running?. is any work been done to the 650 including milling down of the horn?
    what are the jet sizes in the 650cfm compared to the 750cfm

    I have run simliar size motors on the street/strip many times in the past .

    the 650 cfm really was responsive on bottom end..

    i have a 406 ci 460hp steel head ( iron eagle) heads, no port work, 520 lift flat tappet cam...i have out of the box 750cfm ( with horn) and it takes all of it....

    30 more cubic inches is all i see off the top..

    have you checked you plugs after a run ?...be sure to kill it after a full throttle attempt...you can also get a pyrometer to get some exhaust temp readings ..this will tell you lean or fat for sure..

    sounds like your right on top of it to me.

    Brian
    Bjuice..

    "I'M YOUR HUCKLEBERRY ! "

  3. #3
    Senior Member RACING JUNKIE
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    I had the same problem years ago with a near stock 400 sm blk I put a brand new 700 dp on...floor it and it would fall on it's face...EVERYONE KEPT TELLING ME BIGGER SQUIRTER YADA YADA YADA..TOO LEAN...but then I put a new 650 on it AND it came alive...the 700 had a 50 cc pump on the rear and the 650 a 30 cc pump on the secondaries...I figured it was just too much carb for what I had. (low compression small hyd cam) I have been told that 700 DP would not have come with 50 cc pump but this one did and I bought it new.

  4. #4
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    these are 2.02 heads no port work anywhere,the cam is 479 [email protected] .50 2-6 k rev range ,my question i guess is was my 750 that f'ed up or is this 650 more for this set up,it is also topped off with 100 shot of nos,but was squaring away this problem first,the carb also has the stock squirters and 30 cc pumps

  5. #5
    Administrator RACING JUNKIE bjuice's Avatar
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    i think your dead on with the 650 cfm from what i hear..
    By the way how loose is your converter and how much gear ya running ?


    At minimum i would look at bumping up a jet size with the 650 cfm and having it a little fat on the NOS passes.
    i had a 1000 cfm Barry Grant "Silver Claw" on a 406ci in my Bug in 2003..and i had her a little fat when i put the plate on her.


    just a quick story.one of my cars i drove to high school in the early 80's was a 70 camaro with 4.10 gear...350ci with steel crank, a set of steel doule hump 300 hp heads...for those of you that remember AUTO SHACK...i bought a Alliance cam ( hyd lift anti pump up lifters)...460 lift

    I Ran a converter out of a Vega...loosy, goosy..


    to get to my point, i put tunnel ram on the car with s pair of 465cfm Holley carbs....

    It ran like BAT OUT OF HELL....i was the fastest thing around ( street) in 1980-thru 82...

    would drive car to local strip 1 hour away run the gamblers race..and drive home...under $10.00 worth of gas...

    the car ran low 7.90's (1/8th) spinning,,street tires and thru mufflers..
    from a roll on the street it was a JET.

    on the way home the tunnel ram would start frosting up so much i would have pull over and wipe off the windshield from the frost blowing back to the windshield like it was raining.


    ahhh ...the good ole memories...sorry i just got caught up in them...

    bottom line even with this set up less was best in the carb department.

    8)
    Bjuice..

    "I'M YOUR HUCKLEBERRY ! "

  6. #6
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    thanks for the input

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    Senior Member RACING JUNKIE mopar1968's Avatar
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    :? Jet extension's :?:
    Head's up the true drag race!!

  8. #8
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    yes,this this was just never right with the 750,I never had a problem this bad,i took apart the 750 about 12 times hoping to find somthing,i did the powervalve change jets squirters float heights ect................... :?

  9. #9
    Senior Member RACING JUNKIE
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    Have you made a pass with the 650 sometimes what sounds better away from the track doesn't go faster at the track. I think the 750 needs more converter at least 4000. But hect, if your happy with the 650 thats all that matters. Its all about combos. If your footbraking at the track, carb response is whats important for consistant .0 lights. KILL THE TREE!!

  10. #10
    Senior Member RACING JUNKIE jmarksdragster's Avatar
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    Timing? Should be fixed about 37 to 40˚.
    Mark Whitener
    http://racingfuelsystems.myfunforum.org
    __________

    Good work isn't cheap, and cheap work can't be good.


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