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  1. #1
    casual poster Kocho's Avatar
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    Default Quickfuel question

    Hi I have hr 450 on my stroked 253 and the idle is rich, rich enough to see black smoke idling with warm engine no choke the only place it seems to like idling the best is 3/4 turns out thinking of upping the idle air bleeds it has 70s out the box how far up should I go? It has a 276 cam initial timing is 22 total 32 any help would be appreciated

  2. #2
    Do you ever leave? EH179's Avatar
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    Go up about .006 to a 76 and see what happens.

  3. #3
    casual poster Kocho's Avatar
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    Quote Originally Posted by EH179 View Post
    Go up about .006 to a 76 and see what happens.
    Do all 4 corners or just primary side?

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    All 4 mate. Also keep in mind that any adjustment for idle speed on the primary side MUST be the same on the secondary side. Same with mixture screws.

  5. #5
    254RWHP boat anchor EVL253's Avatar
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    first up check throttle blade position.
    pri set them so transfer slots are square at most.
    sec ideally no transfer slot showing.
    dont go fiddling bleeds etc till this is right.
    personally i prefer to shrink the idle jet as its effect is much more noticable
    11 second E85 bottle fed boat anchor

  6. #6
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    Quote Originally Posted by EVL253 View Post
    first up check throttle blade position.
    pri set them so transfer slots are square at most.
    sec ideally no transfer slot showing.
    dont go fiddling bleeds etc till this is right.
    personally i prefer to shrink the idle jet as its effect is much more noticable
    This but leave primary blades alone when adjusting the idle speed only use the secondary's.
    I also recommend starting at 1.5 turns out and getting it proper hot before changing any mixture screws.

    Then tune the screws for maximum vacuum.

    3/4 turn out i have got a qft running around 1/2 out at all four corners and is just fine on a 304 though.

    Every motor is different and when learning carbs my suggestion is get yourself a vacuum gauge and learn to read it they are a very powerful tool for tuning and diagnosis.

    I have a vacuum/boost gauge along with an afr gauge on board it is almost like cheating when setting up the carb.



    Probably could change the idle jet on mine but cbf level is high when it only has a slight flat spot when cold

  7. #7
    Do you ever leave? EH179's Avatar
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    Changing the ifr sizing is something best left to those that know how, or pay dearly for a mistake.

    I'm a believer of doing the easy checks first, and iab's are something most on here can change with no major adverse affects.

  8. #8
    Do you ever leave? EH179's Avatar
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    OK my bad, just realised this model has screw in ifr jets, so no problem changing them.
    I couldn't find what size are installed, to recommend an adjustment though.

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    Quote Originally Posted by EVL253 View Post
    first up check throttle blade position.
    pri set them so transfer slots are square at most.
    sec ideally no transfer slot showing.
    dont go fiddling bleeds etc till this is right.
    personally i prefer to shrink the idle jet as its effect is much more noticable
    Yep.

  10. #10
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    Quote Originally Posted by EH179 View Post
    OK my bad, just realised this model has screw in ifr jets, so no problem changing them.
    I couldn't find what size are installed, to recommend an adjustment though.
    They is 10/32
    Quick fuel sell kits of them of course but not really needed to played with in 99% of applications and really only offer very fine adjustments ie balancing.

    Also if going down this route it is not recommend to change them with the carb on the motor...ask me how i know, you will end up taking the carb off anyway...brass is non magnetic as well...

  11. #11
    casual poster Kocho's Avatar
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    Cheers for the responses fella much appreciated might start with what evl253 said and work from there it does blow a bit of black smoke at idle stings the eyes in the shed and a small flat spot taking off otherwise its fine. I would've taken it off the change the bleeds because my luck they would fall into the motor. Changed my oil the other day smelt a bit fuely been doing a lot of idling lately
    Last edited by Kocho; 13-03-2018 at 05:30 PM.

  12. #12
    254RWHP boat anchor EVL253's Avatar
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    look for my tuning a holley for economy thread here. ok so its converting a model to screw in adjustable that you already have but principles are the same
    11 second E85 bottle fed boat anchor

  13. #13
    casual poster Kocho's Avatar
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    So after some more stuffing around put a pressure guage in the fuel line was fluctuating between 5.5 to just over 8 psi so I've put a regulator on it it now sits happily steady just under 6psi. So will the mechanical fuel pump crap it's self now I've put a regulator on it, it's a goss pump

  14. #14
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    If you have adjustable idel jets in the metering block go down in size on them first . then play with the rest of the carb .

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