Carb doesn't like power valve
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Carb doesn't like power valve

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    Senior Member Luckie Stiff's Avatar
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    Default Carb doesn't like power valve

    Ok, so following the advice of some folks I hold in high regard in the engine world I removed the primary PV plug from my carb, re-jetted it and put a 6.5 PV in it. I did the whole vacuum gauge at idle, cruise, and the hit of the throttle. My boat ran like total shit. Backfiring through the carb, lost almost 5 mph, just not a good day. I put it on the trailer, took the PV out and reinstalled the plug, changed my jetting back to where it was. Boat runs perfect again.

    My question is this, why the hell doesn't my carb like the PV? Holley HP950 choke horn milled & blended, worked by C&J engineering. I'd love a tad more economy but not if I have to deal with the headaches.

    Help!
    "Don't you realize that there are already enough people in the world to hate without you putting in so much effort to give me another?"

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    just a ski boat with bark Carnivalride's Avatar
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    Quote Originally Posted by Luckie Stiff View Post
    Ok, so following the advice of some folks I hold in high regard in the engine world I removed the primary PV plug from my carb, re-jetted it and put a 6.5 PV in it. I did the whole vacuum gauge at idle, cruise, and the hit of the throttle. My boat ran like total shit. Backfiring through the carb, lost almost 5 mph, just not a good day. I put it on the trailer, took the PV out and reinstalled the plug, changed my jetting back to where it was. Boat runs perfect again.

    My question is this, why the hell doesn't my carb like the PV? Holley HP950 choke horn milled & blended, worked by C&J engineering. I'd love a tad more economy but not if I have to deal with the headaches.

    Help!
    Well you didn't give much to go off here so here's a couple questions.
    • what were your primary jets with the plug?
    • What did you change them to with the PV, or did you change them (if not it would be fat with a PV).
    • what was your vacum reading at idle
    • what was it while cruising?


    Have you ever pulled a plug and read it after cruising? If not you might try that next time out to see if it can be safely leaned out any more.


    JMO.
    Quote Originally Posted by gn7 View Post
    Carnivalride, you really need to find some other hobby. You have no talent for this boat thing

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    The PV is part of the Cruise Circit. Theres no vacume , so it doesn't work. You don't need it on race app. or on a tunnel ram app.You are trying to expect vac. you're not creating vac.

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    Senior Member Luckie Stiff's Avatar
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    Quote Originally Posted by Carnivalride View Post
    Well you didn't give much to go off here so here's a couple questions.
    • what were your primary jets with the plug? 86
    • What did you change them to with the PV, or did you change them (if not it would be fat with a PV).80
    • what was your vacum reading at idle10ish
    • what was it while cruising?7ish


    Have you ever pulled a plug and read it after cruising? If not you might try that next time out to see if it can be safely leaned out any more. nice cocoa color on the plugs


    JMO.
    This is a 950 HP on a Team G intake. @ the hit my vacuum dropped to 5.75 so I went with the 6.5 PV
    "Don't you realize that there are already enough people in the world to hate without you putting in so much effort to give me another?"

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    just a ski boat with bark Carnivalride's Avatar
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    Quote Originally Posted by Luckie Stiff View Post

    what was it while cruising?7ish

    Have you ever pulled a plug and read it after cruising? If not you might try that next time out to see if it can be safely leaned out any more. nice cocoa color on the plugs

    This is a 950 HP on a Team G intake. @ the hit my vacuum dropped to 5.75 so I went with the 6.5 PV
    If your engine cruises at 7hg I would have probably started with 5.5 or maybe even a 4.5 to keep it leaned out longer. What do you mean by at the hit? When you mash it and leave it for a few seconds doesn't drop to near 0-2 on the vacum gauge? I'm not sure why it acted up with a PV unless that metering block doesn't have all the provisions for it. Have you tried calling C&J engineering since they reworked it? Maybe they changed some circuits and it won't work with a PV now, not sure just throwing it out there.
    Quote Originally Posted by gn7 View Post
    Carnivalride, you really need to find some other hobby. You have no talent for this boat thing

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    just curious!...what c.u. is the motor?...perhaps the 950 is too big!...maybe a change to an 850 would be a better choice & better fuel economy ...just sayin' my .02 cents

    FastRat

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    Senior Member Luckie Stiff's Avatar
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    Quote Originally Posted by FastRat View Post
    just curious!...what c.u. is the motor?...perhaps the 950 is too big!...maybe a change to an 850 would be a better choice & better fuel economy ...just sayin' my .02 cents

    FastRat
    I've thought about that, but money is kinda tight right now so I gotta make what I got work. Motor is 10.5:1 468 BBC. It's funny, I went and pulled my plugs after I made the original post, the last time I ran it was last weekend, idled to the boat ramp, plugs are a tad too light for my taste, think I'm gonna back the timing down a bit and see what that does.
    "Don't you realize that there are already enough people in the world to hate without you putting in so much effort to give me another?"

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    gn7
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    Quote Originally Posted by FastRat View Post
    just curious!...what c.u. is the motor?...perhaps the 950 is too big!...maybe a change to an 850 would be a better choice & better fuel economy ...just sayin' my .02 cents

    FastRat
    Quote Originally Posted by Luckie Stiff View Post
    I've thought about that, but money is kinda tight right now so I gotta make what I got work. Motor is 10.5:1 468 BBC. It's funny, I went and pulled my plugs after I made the original post, the last time I ran it was last weekend, idled to the boat ramp, plugs are a tad too light for my taste, think I'm gonna back the timing down a bit and see what that does.
    The 950 is not too big. In fact the 950 has a smaller venturi, and the same base plate as a 850. Holley should have never called this carb a 950. It is so misleading it unbelievable.
    My first question would be why your vacuum is 7ish. Just how big is the cam in the thing?
    And you never did post the jetting. And may need MORE timing.
    My gut says your lean, back firing thru the carb, loss if top speed. You LEAN!


    Your going in the wrong direction.



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    Senior Member Luckie Stiff's Avatar
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    Jetting is 86 Primary, 88 Secondary, total timing @ 3000 RPM is 38* What do you suggest GN7?
    "Don't you realize that there are already enough people in the world to hate without you putting in so much effort to give me another?"

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    Another thing to take a look at is the power valve restriction size. This is the the size of the two small holes in the metering block directly behind the power valve. (you can see them when you screw the valve or plug out). If these holes happened not to be drilled, then the pv is not enrichening the circuit at all.

    I have had a couple of Holley performance carbs come in thru the years that did not have the metering blocks drilled. We simply drilled them to size and added the cruise circuit.

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    Senior Member Luckie Stiff's Avatar
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    Ok, for now I'm going to leave the carburetor alone. I'll deal with the lack of fuel economy. My question now is my timing, my plugs looked a little light after my idle to the ramp last weekend. They're more of a dingy grey/white/tan. I'm at 38* total, all in by 3000 RPM. Should I back it down to 36? 34? I really don't want to shitcan a motor at the start of summer...
    "Don't you realize that there are already enough people in the world to hate without you putting in so much effort to give me another?"

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    Try 24* all in at 2,000 rpm. It'll elimenate the vac. adv. Then what ever you adjust the dist. at. add both for total * timming. It'll be real quick.

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    Senior Member Luckie Stiff's Avatar
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    Quote Originally Posted by getrdone View Post
    Try 24* all in at 2,000 rpm. It'll elimenate the vac. adv. Then what ever you adjust the dist. at. add both for total * timming. It'll be real quick.
    24* @ 2K ? That seems a little on the lower side of things, or am I missing something?


    Here's what all of my plugs look like.
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    Last edited by Luckie Stiff; 06-03-2011 at 12:45 PM.
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    Set your curve in the dist. at 24* at 2,000 rpm. Then adj. the dist.Add what is on the crank to the 24* you have curved in the dist. and you have your total. Yes it will be more than 24*. As long as it doesn't want to kick back when starting, then you're there.
    24* + what is on the crank.

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