Barrel valve idle setup?

Discussion in 'PSI Superchargers Tech Questions' started by Compresser, Jan 13, 2021.

  1. Compresser

    Compresser New Member

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    Looking for some insight on correct set up on a cube BV.
    I changed from a K to the cube and am unable to get the idle below 1900 RPM in gear ith out the surge.
    Need a ball park starting point.
    BV is way on the rich side at this time.
    Hilborn shotgun hat, hat nozzles with air.
    Port nozzles with 14 lb check valve.
    Timing locked at 30*
    14/71 HHR blower on alky.
     
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  2. Bjs344

    Bjs344 Member

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    Sounds like blade gap is a little high. Adjust that and then lean it down until it stumbles on a decent throttle crack. Riches it back up a couple flats past stumble. Adjust for cylinder head temp from there. What is your idle poppet set at and where is it located?
     
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  3. Compresser

    Compresser New Member

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    Idle poppet is 10 psi and located at the cube BV. T
    I used the throttle crack on my regulear MFI and it worked very well.
    I just can not get the surge to go away.
    Any suggestion on air gap for throttle blades?
     
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  4. Bjs344

    Bjs344 Member

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    I usually start out with the blades as far shut as they’ll go without binding. Maybe .005 using small points style feeler gages. Those give you a more accurate reading on a butterfly.

    I like my idle to be about 1500 shortly after I fire it. I’m ok with a couple hundred rpm surge (+/-200, so 1300-1700) when it’s a little cold. This usually puts it at a pretty constant (I.e. no surge) 1700-1800 when I’m ready to stage.

    some guys will put push lock connectors in a blower nozzle port with plastic plugs. You can have someone pull the plugs at cold idle and then put them back in. I’ve always thought that was a little silly, why not just let it lope for the first 30 seconds. I do have them but only use them as a place to put the primer bottle

    I also use the timing table to smooth out the cold idle. I set a saddle point in the timing curve wherever I want it to idle at hot. Add 2-3 degrees below that, subtract 3 degrees right above it for a couple hundred rpm.
     
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  5. Compresser

    Compresser New Member

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    BJ thank you for the info.
    Funny about the squirt bottle.
    I use an electric priming system.
    Every one that helps me is afraid to use a starting bottle.
     
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  6. Bjs344

    Bjs344 Member

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    Ya, i stumbled across that last year after having people squirt through the butterflies for years. Almost always at the head of the lanes it was: fire, die, respray, fire.

    I was by myself and determined to get a new combo started up in the shop. After about 15 attempts to spray through the butterflies and then hit the starter button and then try to reach back up to spray the butterflies again, I realized my bottle would fit in that pushlock deal. I actually kept it running for awhile like that because, as it turned out, I had the pump set up backwards.

    It will scare the crap out of people that haven’t done it before because you can spray hard enough that the bottle kinda fires itself out of the hole, and if you’re lucky it does it right when the car lights which makes it almost impossible not to have a heart attack. Good entertainment
     
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