holley jets... wtf???
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holley jets... wtf???

  1. #1
    "BOUGHT NOT BUILT" 2FORCEFULL's Avatar
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    Default holley jets... wtf???

    took the haskel out to mead today, I put a new carb (holley 750 vac. sec,)

    been out a while.. boats runn'n strong...not shoot'n ducks or nothing
    but feels like it's on kill..

    so I pull a plug... sure as shiat... whiter than false teeth...

    I like em with that light chocolate milk color..

    so I come home and dig out my old holley jet box...

    it has 72s... so I'm think'n 74s or 76s

    well, I pull out a couple 74s, just look'n at them the 74s look smaller..

    so I index them and sure enough they are smaller...

    I noticed that the jets with the number on the side are bigger than
    the ones with the number stamped on the top...

    seems like i remember someting about that... but forgot??
    anyone know whats up???

    I ended up putting the 76s in,... and gonna bring the 74s to test tomorrow..

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    Senior Member EVILFORCE's Avatar
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    I remember when they changed their numbering system Longggggg time ago. Like 20 years. I had a chart that told you what the new numbers were.
    No Fool Like A Old Fool is there?

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    "BOUGHT NOT BUILT" 2FORCEFULL's Avatar
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    Quote Originally Posted by EVILFORCE View Post
    I remember when they changed their numbering system Longggggg time ago. Like 20 years. I had a chart that told you what the new numbers were.
    lol... I think my jet box is 30+ years old...

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    Senior Member EVILFORCE's Avatar
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    Quote Originally Posted by 2FORCEFULL View Post
    lol... I think my jet box is 30+ years old...
    Mine too.
    No Fool Like A Old Fool is there?

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    Cas
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    not sure if this will help or not but it's a chart showing the current Holley jet numbers and the orifice size-



    Holley measures the jets by flow and not really the size of the orifice. If you look closely at the jets, like 80, 81 and 82 with the same size orifice, they have different entries and exit angles
    Last edited by Cas; 05-24-2010 at 08:30 PM.

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    Super Moderator HammerDown's Avatar
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    Quote Originally Posted by Cas View Post
    not sure if this will help or not but it's a chart showing the current Holley jet numbers and the orifice size-



    Holley measures the jets by flow and not really the size of the orifice. If you look closely at the jets, like 80, 81 and 82 with the same size orifice, they have different entries and exit angles
    Good post Cas
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    Cas
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    Quote Originally Posted by HammerDown View Post
    Good post Cas
    thanks! I found that chart a couple years ago, figured it would come in handy someday
    Last edited by Cas; 05-24-2010 at 09:14 PM.

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    "BOUGHT NOT BUILT" 2FORCEFULL's Avatar
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    Quote Originally Posted by Cas View Post
    thanks! I found that chart a couple years ago, figured it would come in handy someday
    big thanks here Cas...I'm getting old and sometimes I look at something and say...
    "I used to know how to do that"

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    "BOUGHT NOT BUILT" 2FORCEFULL's Avatar
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    well, I run the 76s....she's still lean...

    it came stock w/72s
    how big can I go with out afr problems???

    I'm gonna try 80s and bring 78 with me...

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    Senior Member TwinTurbo540's Avatar
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    In my experiences it takes a big jump to make a change in a jet boat....I would put the 80's in and start there. Why not just bring the whole jet kit??

    Travis
    I like my women like I like my boats......Fast and ready to get wet at all times!!

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    Quote Originally Posted by TwinTurbo540 View Post
    In my experiences it takes a big jump to make a change in a jet boat....I would put the 80's in and start there. Why not just bring the whole jet kit??

    Travis
    the carb is a 750 vac, secondary... came with 72s= .079

    80s would be .093

    i have some .103s

    how big of jet can you run in a 750?

  14. #12
    B1 Racing cs19's Avatar
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    To do an accurate plug reading you need a plug reading tool like a doctor uses to look into your ears. You need to be looking deep down the porcelain and looking for a fuel ring. Pulling a plug and just looking for a chocloate milk appearance is NOT the way to read a spark plug. White porcelain is a good thing as long as you have a little fuel ring down at the bottom.

    Your jetting may be ok where its at.

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    Default Diameter vs AREA

    Quote Originally Posted by Cas View Post
    thanks! I found that chart a couple years ago, figured it would come in handy someday

    Granted, the numbering system changes are needed, new to old, but truth be told,
    there is a much better chart that shows actual "area" of the various diameters. When dealing with air density, tuning corrections are done on a percentage basis. Example: the .093 jet has an area of .0067929, where the .079 has an area of .0049017........Once you establish a performance "baseline" at a given air density, and flow area, you can easily reach the same F/A ratio using density change percentage, to area change percentage, to a "gnat's ass"........Without having to stop and do the conversion math from diameter to area.......Just saying, when you're looking for that last ounce of HP.......Ray

    PS This is extremely helpful when running at different altitudes, or changing weather conditions....
    Last edited by Moneypit; 06-04-2010 at 08:38 AM.
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  16. #14
    "BOUGHT NOT BUILT" 2FORCEFULL's Avatar
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    Quote Originally Posted by cs19 View Post
    To do an accurate plug reading you need a plug reading tool like a doctor uses to look into your ears. You need to be looking deep down the porcelain and looking for a fuel ring. Pulling a plug and just looking for a chocloate milk appearance is NOT the way to read a spark plug. White porcelain is a good thing as long as you have a little fuel ring down at the bottom.

    Your jetting may be ok where its at.
    I tryed at the lake with a magnify glass with the sun shinnig down in there,

    nothing...

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