Power valve???
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Power valve???

  1. #1
    Senior Member junkyard's Avatar
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    Default Power valve???

    Im running a stock 460 in a 18' jet with a holley 750 vacume seconddaireis/power valve and 76 jets in Phoenix about 1200 ft. For some reason my boat burns through 2-3 time ass much gas as some of these other boats that have bigger motors and run higher RPM's. If I block the power vale and up the jets will it do anything for me. I have herd you need the power vale and aslo that the jets dont need them. So whats your thought on the power valve and ideas on what I should look at in my boat so that Im not haveing to fill up three times a day at the lake? THX

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    Resident Ford Nut Sleeper CP's Avatar
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    What numbers are on the pv 85-75-65-55 ? Are they front and rear ?

    Keep the PV find out what wrong with the system. I'm not fond of 750's or Vac/ sec on 460's or 454's, but you can make them work fine.

    One year we blew up our stout 472" Roller cam engine and replaced it with a near stock 460. The near stock engine used twice as much fuel the weekend it was in the boat. Way more throttle effort less power and it sucked fuel like a mofo.

    On the PV's try a 55 pv, best if you can put a vac guage on it while running on the water to check the vac at cruising speed then put a PV in that's 2" less vac than that number.

    Good luck. Oh the 565" carb runs a primary PV and uses very little fuel in the 2,800-4,000 rpm range.

    Sleeper CP
    Last edited by Sleeper CP; 02-13-2009 at 12:22 PM.

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    460
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    Might be sumthing else going on. When was the last time the carb was rebuilt? How about plugs cap etc. I venture to say you need to give her a tune up and rebuild the carb. I have power valves in both side of my dominator. Keep in mind jetting up might make it run rich and use more gas then it is right now.

    Have you done a plug reading to see if its running rich right now?
    Last edited by 460; 02-13-2009 at 10:15 AM.

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    Quote Originally Posted by junkyard View Post
    If I block the power vale and up the jets will it do anything for me. I have herd you need the power vale and aslo that the jets dont need them. sphss
    Sorry about that. If you remove the PV "typically" they are worth 6-8 jet sizes. So you should jet up at least 6 jet sizes. I've done it before and boy did our boat such some gas.

    Keep the PV's and get it tuned. See if you can borrow an 850 from someone and see what happens.

    Sleeper CP

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    ok...laugh if u must! ...from past experiences with the BBF (FE's & 460's) i have found that a Edelbrock 650/750cfm carb seems to work the best for gas consumption on a stock motor...i have alot of friends that run both types of motors & get very decent gas mileage...IMO & others also, i dont think a vac sec carb is a good idea on a jet boat...if it were mine, i would either try a Edelbrock 750cfm carb or a Holley 650cfm DP mech sec carb...no matter which way or how u go, get rid of the vac sec carb ...just my .02 cents

    FastRat

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    Senior Member junkyard's Avatar
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    The carb was rebuilt last season by a carb shop.Its always used alot of gas.The plugs look good.If I remember corectly The boat runs about 3500 RPM's maybe a little more. Not sure if the tack is working properly though.# on the pv is 6.5 and only in the rear,thers no metering plate in the front.
    Last edited by junkyard; 02-13-2009 at 12:41 PM.

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    Quote Originally Posted by junkyard View Post

    # on the pv is 6.5 and only in the rear, theres no metering plate in the front.
    what is the List# on the airhorn?...i have never seen a vac sec carb as u describe!!!...also...what type of manifold do u have on it?

    FastRat

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    460
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    Quote Originally Posted by FastRat View Post
    what is the List# on the airhorn?...i have never seen a vac sec carb as u describe!!!...also...what type of manifold do u have on it?

    FastRat
    3310-2 is a 750CFM vac secontary carb. That could be it

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    E-7 Sheepdog (ret) SmokinLowriderSS's Avatar
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    Quote Originally Posted by junkyard View Post
    Im running a stock 460 in a 18' jet with a holley 750 vacume seconddaireis/power valve and 76 jets in Phoenix about 1200 ft. For some reason my boat burns through 2-3 time ass much gas as some of these other boats that have bigger motors and run higher RPM's. If I block the power vale and up the jets will it do anything for me. I have herd you need the power vale and aslo that the jets dont need them. So whats your thought on the power valve and ideas on what I should look at in my boat so that Im not haveing to fill up three times a day at the lake? THX
    What are teh 4-corner jets?

    I run a mech, sec, with a PV, jetted 67 front, 77 rear, 6.5" power valve in the front.

    The one time/summer I tried the "ditch the PV" thing, Close was 6 sizes, then, there was such a big hole off idle that huge ammounts of accel pump & shooter dancing was gouing to be needed.

    Better off to leave it as designed and get it adjusted right. The side with a power valve should be jetted smaller, if it's jetted 76 square, with a power valve on one side, that side is badly rich part of the time.
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    Maybe you need one of these under your pedal.
    Attached Images Attached Images  
    Quote Originally Posted by HawaiianJet View Post
    You done got my kentucky ass all confused!!!

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    Senior Member junkyard's Avatar
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    Quote Originally Posted by TrynPas View Post
    Maybe you need one of these under your pedal.
    That would help the fule issue but then I have to wory about the fisherman passing me with there troleing motors.

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    You may be running with the secondaries open and not know it, You might need to check this out as well, and put a heavier spring in the secondary.

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    Quote Originally Posted by SmokinLowriderSS View Post
    What are teh 4-corner jets?
    Where do I finde thoughs jet?
    After takeing the pictures, I was rong. The pv is in the front.
    1st pic is front with pv
    2nd is back, no jets
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  16. #14
    Senior Member cave's Avatar
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    Quote Originally Posted by junkyard View Post
    Where do I finde thoughs jet?
    After takeing the pictures, I was rong. The pv is in the front.
    1st pic is front with pv
    2nd is back, no jets
    In the 4 corners

    Josh what color are the plugs about mid way down the electrode?
    I noticed in your 3rd photo, your air bleeds need some cleaning.
    Last edited by cave; 02-13-2009 at 06:09 PM.
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