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  1. #16
    Senior Member GASSD6's Avatar
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    cheers m016922 thats the plan.

    350lj - its a holley 650 ultra dp, we didnt try modify the emulsions like i said it only has the bottom hole with a fixed brass sleeve an the middle 2 are blocked off, we initially thought we had a blockage some where so we tried a near new ultra 650 (same carb) and it had the exact same issues. yeah no dramas with carb everywhere else it performed real well just the idle id like to clean up and get in under 1200rpm would be nice. ill look into billet meetering blocks or try for a new qf650.

  2. #17
    Not the Kingswood! hq308's Avatar
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    Try screwing the mixture screws 1/2 turn out (richer) from where they are now.

  3. #18
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    Can you get hold of some old standard 750 metering blocks with 2 emulsions to try . You dont need to buy a new carb . 350lj


    Quote Originally Posted by GASSD6 View Post
    cheers m016922 thats the plan.

    350lj - its a holley 650 ultra dp, we didnt try modify the emulsions like i said it only has the bottom hole with a fixed brass sleeve an the middle 2 are blocked off, we initially thought we had a blockage some where so we tried a near new ultra 650 (same carb) and it had the exact same issues. yeah no dramas with carb everywhere else it performed real well just the idle id like to clean up and get in under 1200rpm would be nice. ill look into billet meetering blocks or try for a new qf650.

  4. #19
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    Pretty sure the top emulsion jet is idle/cruise. Can you lean the idle out a bit with that?

  5. #20
    Senior Member GASSD6's Avatar
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    Hq308 - the screws are 1 turn out atm, thats about the best we could get it to get it to idle ok still to high @ 1200rpm
    It just needs more Air at idle thats why we drilled 4 small holes in butterflys to help it so we could get some adjustment back on the mixer screws, cause before the holes it didnt matter where we had screws it wasnt effecting it at all.

    350lj - Yeah i can look into other meetering blocks, yeah the carby performed well every where else so i no its ok. ( didnt really want a new carb so ill sus out some different blocks )

    CAstiron355 - Yeah id have to do a small modification to the top delivery hole and tap a thread in there to take an adjustable jet it can be done, just have to play around with it abit more.

  6. #21
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    Ahh right. Thought the top one was adjustable on yours.

  7. #22
    Not the Kingswood! hq308's Avatar
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    So when you say you can't get it to idle under 1200 is that because it won't run under 1200 or because you physically have the idle screws backed out all the way and it still idles at 1200?

    If it's idling at 1200 it's got enough air, the reason the idle screws where unresponsive previously is because you would have had the transfer slots exposed (prior to drilling the throttle plates). By the sounds of things you most likely have low vacuum at idle which is why it needed the holes in the throttle plates. Engines with low vacuum (usually) need to be richened up at idle to compensate for the poor atomisation of fuel due to the low vacuum. How much does your idle rpm currently change going from drive to neutral?

  8. #23
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    Can you post up a photo of the blocks you have with the emulsions showing .
    350lj

  9. #24
    Do you ever leave? EH179's Avatar
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    Quote Originally Posted by hq308 View Post
    So when you say you can't get it to idle under 1200 is that because it won't run under 1200 or because you physically have the idle screws backed out all the way and it still idles at 1200?

    If it's idling at 1200 it's got enough air, the reason the idle screws where unresponsive previously is because you would have had the transfer slots exposed (prior to drilling the throttle plates). By the sounds of things you most likely have low vacuum at idle which is why it needed the holes in the throttle plates. Engines with low vacuum (usually) need to be richened up at idle to compensate for the poor atomisation of fuel due to the low vacuum. How much does your idle rpm currently change going from drive to neutral?
    I concur...and now with the plates drilled, it may be even harder to get right.
    Waiting on the answer to the rpm drop question.

  10. #25
    Senior Member GASSD6's Avatar
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    hq308 - yes is wont idle correct under 1200 and sorry i should of explain it a bit clearer, yes has about 6hg at idle running a harrop high rise, 11:1 comp, come alloy heads with a 288 solid cam.

    id say it drops around 250 rpm in gear and some time need to just give pedal a lil pump to keep it running.
    we checked transfer slots and yes they were open abit but adjust idle to close it and it just wouldnt idle, it would for a few seconds and then just die off and you would have to stab it to keep it going. being an holley no adjustable screw for secondarys, so we took it off and opened rear butterflys which help it alot ( which we knew then it needed more air) but lost signal to adjustments screw so thats why we drilled the holes. which gain us back our adjustment.

    350lj - when i take off ill get some photos.

  11. #26
    Senior Member GASSD6's Avatar
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    Quote Originally Posted by 350lj View Post
    Can you post up a photo of the blocks you have with the emulsions showing .
    350lj
    HI 350lj my apology i just took off the fuel bowls for a look and i must of been mistaken listing to dyno man about emulsion channels being blocked for some reason, the holley has 2 channels and the qf has 3. but qf has an adjustable idle feed restriction Holley has none.
    iv seen the modification you can do, tap thread and run restriction jets and get rid of the brass tube on bottom inlet hole

    20180419_204515.jpg

  12. #27
    Not the Kingswood! hq308's Avatar
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    Try 1/2 turn richer on the primaries and see how much the idle then drops between neutral and drive. I've had the same issue in the past and it just needs to be a little richer to overcome the lack of vacuum. If you're tuning the idle to a number on an AFR gauge it will likely need to be richer than you expect.

    Next time you have the carb off remove the secondary adjustment screw and put it in backwards so the slot is facing up. When you want to do adjustments you just shut the engine off crack the throttle open and access the screw from the top of the carb while it's still fitted. While the carbs off make sure the primary T-slot is correctly adjusted and from then on do all your idle speed adjustments using the secondary screw.

  13. #28
    Senior Member GASSD6's Avatar
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    Quote Originally Posted by hq308 View Post
    Try 1/2 turn richer on the primaries and see how much the idle then drops between neutral and drive. I've had the same issue in the past and it just needs to be a little richer to overcome the lack of vacuum. If you're tuning the idle to a number on an AFR gauge it will likely need to be richer than you expect.

    Next time you have the carb off remove the secondary adjustment screw and put it in backwards so the slot is facing up. When you want to do adjustments you just shut the engine off crack the throttle open and access the screw from the top of the carb while it's still fitted. While the carbs off make sure the primary T-slot is correctly adjusted and from then on do all your idle speed adjustments using the secondary screw.
    yeah great idea mate, i was just looking at the qf carb and i thought i could just buy the Secondary cam bracket from qf an put on my holley easy fix. i will give that a go an see if it helps, as ya say it was real rich at idle anyway thats why i think he was stuffing around with it some much to get it down a bit.

  14. #29
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    What's your initial timing set at?

  15. #30
    Senior Member GASSD6's Avatar
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    Quote Originally Posted by Castiron355 View Post
    What's your initial timing set at?
    Not 100% on initial but it has total of 31deg. running an msd pro billet blaster coil and digital 6AL box

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