Adjusta-A-Jet???
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Adjusta-A-Jet???

  1. #1
    The Good mrjoshua's Avatar
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    Default Adjusta-A-Jet???

    Has anyone used the adjustable metering plates form Percey's on their Holley carbs? I am still trying to get my carb tuned right and will be messing with it at the lake this spring. Just wondering if these work well. Trying to keep from draining fuel and pulling the bowls every time. Or should i look into the bowls that allow me to remove the jets through them? Thanks. Happy and safe 2012 to everybody

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    Senior Member jms-1's Avatar
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    my father in law just installed a set . he said it worked good and hasn't had any problems with them yet.

  4. #3
    Member hollbrow's Avatar
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    Default Have looked...

    around trying to find info on those adjustable blocks myself- can't decide what to make of it. Read a lot of stuff on the net and came away with mixed info on the things. Some folks love em' some folks don't. Seems I recall reading at least 1 thread somewhere about some folks having gasket sealing troubles when using them. Dunno if they had bad/wrong gaskets or there was a problem with the block. Seems like a good idea to me.

    I have the quick change bowls on my deal- and they work pretty good- definately beats having to disassemble everything.

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    Default Thanks....

    Thanks Joshua for reminding me why I love mechanical injection.... With a Kinsler "quick disconnect" main pill holder I can change a pill in 30 seconds and the fuel "spillage" is very minimal...I do sympathize with your efforts at your altitude, it's gotta be a bitch with very little air to work with....That said, the drag guys, (asphalt), have been using the "quick jet" bowls for decades, and there are a lot of different ones out there to choose from.....Don't hesitate to call if I can help with that carburetor....
    Ray
    PS Buy an "Air density" gauge, bring the boat down to the river, (very close to sea level), and establish a "baseline" to tune from.... Then it's just simple math to make the corrections to your high altitude boating area based on the air density readings.....Trust me, it works......
    LOUD BOATS SAVE LIVES

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    The Good mrjoshua's Avatar
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    Quote Originally Posted by Moneypit View Post
    Thanks Joshua for reminding me why I love mechanical injection.... With a Kinsler "quick disconnect" main pill holder I can change a pill in 30 seconds and the fuel "spillage" is very minimal...I do sympathize with your efforts at your altitude, it's gotta be a bitch with very little air to work with....That said, the drag guys, (asphalt), have been using the "quick jet" bowls for decades, and there are a lot of different ones out there to choose from.....Don't hesitate to call if I can help with that carburetor....
    Ray
    PS Buy an "Air density" gauge, bring the boat down to the river, (very close to sea level), and establish a "baseline" to tune from.... Then it's just simple math to make the corrections to your high altitude boating area based on the air density readings.....Trust me, it works......
    Thanks Ray. Great to hear from you! I would love to make a "testing" trip down to the river and meet you there. Thanks for the info. I just don't know enough about carb tuning in general much less at high altitudes. I hope your "retirement" is going well. You need to find a few "boat mates" to make your lake tour with you!

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    Default Density gauge

    Quote Originally Posted by mrjoshua View Post
    Thanks Ray. Great to hear from you! I would love to make a "testing" trip down to the river and meet you there. Thanks for the info. I just don't know enough about carb tuning in general much less at high altitudes. I hope your "retirement" is going well. You need to find a few "boat mates" to make your lake tour with you!
    You'll need YOUR OWN density gauge. While they are calibrated, they are not necessarily all going to read the same. You'll need to be able to compare apples to apples based on percentages and jet AREA changes, not diameter changes.... I have charts with sizes carried out 6 places, and once you get a base line at a given density it gets real easy.....
    Ray
    LOUD BOATS SAVE LIVES

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    Senior Member Bigblockbill's Avatar
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    Unless your trying to tune to the .005 and really understand the Density Air I would say no to adjustable jets (To much chance to go the wrong way and be way off). Put some jets in; run the boat look at RPM; change jets; and keep repeating until max RPM. There may be 1 jet difference from good air to bad air but heck thats in the noise for most of us, specially if your just bracket racing at the Butte anyway. It just takes a couple mins per jet change so if you go somewhere else its easy enought to pull the bowls and change them. Get it set here then go to sea level or something and its 3-4 jets... usually even though I have proven that wrong on a 120 degree day at Havasu where I ended up only 1 jet different.

    What carb/motor... bet I can get you a good starting place
    Last edited by Bigblockbill; 01-05-2012 at 11:04 AM.
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    Glendale Arizona Squirtcha?'s Avatar
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    Quote Originally Posted by Bigblockbill View Post
    It just takes a couple mins per jet change so if you go somewhere else its easy enought to pull the bowls and change them.
    Be glad you've only got one carb and the bowls are easy to get to.

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    The Good mrjoshua's Avatar
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    It'S the 468 in the above pic. 9.5:1 hyd roller cam on a dual plane right now but going to try a single plane for a little more top end. HEI (don't remember what it's set at.) The carb is a holley 850 with mec. secondaries. Have 6.5 PV's jets are 80's with 30.cc primary and 50.cc secondary accel. Pumps. I can't remember the shooter size. I blocked off the pv's last season and it kept getting lean on the top end and cutting out. Turned out the enrichment screws and I sized up twice on the jets to no avail. Put the pv's back in and advanced the timing a touch and it ran better. I'm getting just under 5200 rpm. I keep thinking there is more there, but doesn't everybody? What i know about theses carbs are what i've read from the Holley tech book. I know some will say to have vac. Secondaries, but i can just cruise on plane on the primaries with the linkage set right. Saved a ton of gas.

  12. #10
    Senior Member Bigblockbill's Avatar
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    I would think 80's and PVs is a touch too rich however your close. (Note: The PV circuit is worth 6-8 jets) if it were me I would block off the PV's again and put 84s in it, jet boats don't seem to benifit from PVs IMO. The Air/Fuel screws do nothing at WFO and very little if anything other than at idle. Assuming your fuel pump and fuel lines can keep up at WFO ifs its lean popping at WFO keep going up in jets 2 sizes at a time front and back till it stops and you got it. I don't know where you got the timing but I would set it at 39-40 degrees for the butte.

    Also you will definatly benifit from a single plane intake, Victor Jr maybe? Seems as if the dual plane only makes more torque up to about 2500 rpm then the single plane makes more power from there up and jet boats don't ever do anything but idle below 2500. One interesting note I played with a 2" spacer like you have there and just taking it on vs off was a 2-4 (?) jet size different I recall. I think with it on it need bigger jets and figured it was due to the air flow velocity being slower thru the carb with the spacer and hence not pulling as much fuel, but that was years ago and I maybe backwards now. But most motors usually make more power with a spacer.

    What cut impeller is in the pump? And don't go with a vac secondary carb.
    Last edited by Bigblockbill; 01-07-2012 at 06:04 PM.
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  13. #11
    The Good mrjoshua's Avatar
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    Quote Originally Posted by Bigblockbill View Post
    I would think 80's and PVs is a touch too rich however your close. (Note: The PV circuit is worth 6-8 jets) if it were me I would block off the PV's again and put 84s in it, jet boats don't seem to benifit from PVs IMO. The Air/Fuel screws do nothing at WFO and very little if anything other than at idle. Assuming your fuel pump and fuel lines can keep up at WFO ifs its lean popping at WFO keep going up in jets 2 sizes at a time front and back till it stops and you got it. I don't know where you got the timing but I would set it at 39-40 degrees for the butte.

    Also you will definatly benifit from a single plane intake, Victor Jr maybe? Seems as if the dual plane only makes more torque up to about 2500 rpm then the single plane makes more power from there up and jet boats don't ever do anything but idle below 2500. One interesting note I played with a 2" spacer like you have there and just taking it on vs off was a 2-4 (?) jet size different I recall. I think with it on it need bigger jets and figured it was due to the air flow velocity being slower thru the carb with the spacer and hence not pulling as much fuel, but that was years ago and I maybe backwards now. But most motors usually make more power with a spacer.

    What cut impeller is in the pump? And don't go with a vac secondary carb.
    The impeller "was" an A. It ate itself up and started to gaul with the wear ring. It left pretty hard so i was thinking of an a/b to try and get a little more on the top end without giving up much on the holeshot.

  14. #12
    Senior Member Bigblockbill's Avatar
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    So if it was an A at 5200 RPM either it loads the pump super hard or the motor is not making a ton of power. Does it have a loader or just a rock grate? You could go with an a/b and the RPM will pick up a few... does not mean the boat will go any faster though but it might. What cylinder head is on it? Also I think the 850 holley double pumper is a perfect carb for what you have. What MPH is the boat running?
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