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need intake advice

  1. #1
    Senior Member nikwho's Avatar
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    Question need intake advice

    I just aquired a 21' kachina daycrusier with a berkley pump and a BBF. The BBF is at the machine shop getting vatted, bored and an eagle specialties 521" stroker kit. Aside from the eagle specialties kit, im not sure of many particulars. Im not sure of the heads either. I do not have an intake but i have a 780cfm holley 4150 carb sitting in my garage. Im trying to get away with that carb for now. Not sure if its really big enough for the engine or not. Im curious if this intake will work well or what i should plan on running. this is kind of a budget build up. im not out to race, but want a well performing boat. thanks, Nikhttp://www.performanceboats.com//showthread.php?t=30523

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    Boat Nut sleekcrafter's Avatar
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    Single plane hi-rise, Single carb tunnel rams are no good. You will find your self way under carbed for jet boat application, but if you need to get by, it will work.

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    Senior Member nikwho's Avatar
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    so, any advice on what to buy? i have a friend that has a matching carb to mine, but im assuming that dual 780cfm holley 4150's would be too much carb... am i wrong? I do NOT have much knowledge or experience with matching engine components so if you guys can kind of steer me in the right direction, it would be greatly appreciated...

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    Senior Member H20MOFO's Avatar
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    Default more info- heads ,cam, impeller cut, rpm range ect.

    Sleek has given you good info based on what you've posted. I'm not the brightest crayon in the box but 2 carbs are twice the headache. I assume your 780 is a vac secondary, most don't prefer those in a boat application. I'm thinking your 780 is too small, but I have no room to talk I have a 800 dp on a 557, lol
    Another Hot Boat refugee

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    Senior Member nikwho's Avatar
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    gracias.....I will post all specs when i get them from the machine shop tomorrow. I appologize, this is kind of a duplicate post. its in the jet boat section too. if i had a second 780cfm holley, would that be WAY too much carb??? again, this will most likely be more easily answered after cam, head and compression info is posted....

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    Senior Member ol guy's Avatar
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    Quote Originally Posted by nikwho View Post
    I just aquired a 21' kachina daycrusier with a berkley pump and a BBF. The BBF is at the machine shop getting vatted, bored and an eagle specialties 521" stroker kit. Aside from the eagle specialties kit, im not sure of many particulars. Im not sure of the heads either. I do not have an intake but i have a 780cfm holley 4150 carb sitting in my garage. Im trying to get away with that carb for now. Not sure if its really big enough for the engine or not. Im curious if this intake will work well or what i should plan on running. this is kind of a budget build up. im not out to race, but want a well performing boat. thanks, Nikhttp://www.performanceboats.com//showthread.php?t=30523
    If you can find one, a stealth single high-rise and an 850cfm holley would be a good starting point. IMLAO the first person to ask is the guy setting up the motor! Also a 780 holley on that motor will rattle the pistons right out! A 780 will never feed a 521 inch ford. Edelbrock also makes a simular manifold that may be easier to find! M

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    A Edel. Victor with a 1050 Dom.

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    Senior Member Camoman's Avatar
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    Quote Originally Posted by 058 View Post
    A Edel. Victor with a 1050 Dom.
    What he said
    There's doing it easy,or there's doing it better

  11. #9
    Senior Member nikwho's Avatar
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    I have all of the engine info. It is a 460 block, stock heads. It has an Eagle Specialties internally balanced rotating assembly.. Im told that it is about or just a hair over 11:1 compression. .030 over on the bore, ESP forged steel H-beam rods. It has a comp cam.
    Cam grind card reads as follows:

    Grind # FF XM 270H-12
    valve adjustments HYD/HYD
    gross valve lift .554(intake) .557(exhaust)
    duration @ .oo6 tappet lift 270(i) 286(e)
    valve timing open close
    @.006 Int: 25 BTDC 65 ABDCF
    EXH: 77 BBDC 29 ATDC
    specs for cam installed @110.0 intake center line
    Duration @ .050 Int: 226 EXH:236
    lobe lift .3200 .3220
    Lobe separation 112.0

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    Quote Originally Posted by nikwho View Post
    I have all of the engine info. It is a 460 block, stock heads. It has an Eagle Specialties internally balanced rotating assembly.. Im told that it is about or just a hair over 11:1 compression. .030 over on the bore, ESP forged steel H-beam rods. It has a comp cam.
    Cam grind card reads as follows:

    Grind # FF XM 270H-12
    valve adjustments HYD/HYD
    gross valve lift .554(intake) .557(exhaust)
    duration @ .oo6 tappet lift 270(i) 286(e)
    valve timing open close
    @.006 Int: 25 BTDC 65 ABDCF
    EXH: 77 BBDC 29 ATDC
    specs for cam installed @110.0 intake center line
    Duration @ .050 Int: 226 EXH:236
    lobe lift .3200 .3220
    Lobe separation 112.0
    Just casually looking at your cam specs and your build it appears to me that your cam is too small which will make your dynamic C/R too high for pump gas. Even a static C/R of 11 to 1 with a much bigger cam will be too high for pump gas unless your tuneup is dead nuts on. Plan on running race gas?

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    Senior Member Widetrack's Avatar
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    Quote Originally Posted by ol guy View Post
    If you can find one, a stealth single high-rise and an 850cfm holley would be a good starting point. IMLAO the first person to ask is the guy setting up the motor! Also a 780 holley on that motor will rattle the pistons right out! A 780 will never feed a 521 inch ford. Edelbrock also makes a simular manifold that may be easier to find! M
    X2 On the Stealth! Good all around intake!


    SOMEONE SAID YOU CAN'T TAKE IT WITH YOU! SO,IM BURNING IT UP ONE GALLON AT A TIME!
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  14. #12
    Senior Member nikwho's Avatar
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    I DO NOT want to run race gas! The pistons are SRP Part #240856. 4.390 bore inverted dome. comp height 1.350. Is there any way to verify the compression ratio?

  15. #13
    Senior Member H20MOFO's Avatar
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    To find your static you need to know how many cc's your heads are, and the cc's of your pistons, inverted dome means they will have a neg.# . I doubt you have 11 to 1 with an inverted dome, but maybe that's possible with a ford???? That's what I call a closed chamber head.lol As others stated your dynamic is the one that counts, cam plays heavily into this #. A cam with a lot of overlap, and/or a narrow lsa will tend to bleed off some of that compression. Aluminum heads would help you pull off a higher comp. # as would running at altutude.
    Another Hot Boat refugee

  16. #14
    Senior Member nikwho's Avatar
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    Well, I thought that with a dished piston, or neg. dome, 11:1 seemed high. way high... Im not sure of the heads, i dont have them with me, they are in a friends shop. I have been told that they are stockers.. im not sure how many different cc heads were available from ford. I posted the piston part number from srp hoping that someone could check it and tell me what comp ratio i will be at. I live at 7000 feet. the local lake is at 6500ft. I will be primarily running the boat at havasu and lake mojave. maybe up at powell too.. the amount of neg. dome is not specified on the box the pistons came in.

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