what is the biggest cam for a jet boat
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what is the biggest cam for a jet boat

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    Default what is the biggest cam for a jet boat

    My jet boat is a 460 pi in a baja hull it has a crane cam 294B-8 . I want to know if I can put a bigger one . I have stock water cooled headers. Inverted dome pistons stealth. Intake and police intercepter head that have been ported to match scj heads . And a 850dp .

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    Resident Ford Nut Sleeper CP's Avatar
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    What rpm range do you want to run it in? Max rpm and roller cam or hyd or solid flat tappet?

    What are the specs on that Crane cam? and what does it spin now?

    S CP

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    Default 650 hp on pump gas

    It turns 8000 rpms. Cam solid flattaped . I don't know all the spec on the cam . I just got the boat . And started taking apart the engine. I want to get about 650 hp. Out of it .on pumped gas . Can anyone point me in the right direction. I am new to all of this . Thanks

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    Quote Originally Posted by bigdaddy4820 View Post
    It turns 8000 rpms. Cam solid flattaped . I don't know all the spec on the cam . I just got the boat . And started taking apart the engine. I want to get about 650 hp. Out of it .on pumped gas . Can anyone point me in the right direction. I am new to all of this . Thanks
    Better check out your tachometer. Sounds like it may have a setting for 4/6/8 cylinders, and it's on the 4 cylinder setting, not very likely that you are turning 8000 rpm.

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    Senior Member DuaneHTP's Avatar
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    Your numbers do not compute! As said above, check your tach, check the condition of your pump. Give us the size of your impeller. Something is not right here. 460 fords don't turn 8000 rpm and live. (nothing does for long).

    Duane HTP

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    Senior Member swtd's Avatar
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    Default cam

    will be using a 800 lift solid roller in a 540 injected motor next year

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    Quote Originally Posted by bigdaddy4820 View Post
    My jet boat is a 460 pi in a baja hull it has a crane cam 294B-8 . I want to know if I can put a bigger one . I have stock water cooled headers. Inverted dome pistons stealth. Intake and police intercepter head that have been ported to match scj heads . And a 850dp .

    Here are the specs for your cam :

    Adv. Duration I / E: 294 / 304
    Basic RPM Range: 3500 - 6500
    Dur. @ 0.050 I/E: 256 / 266
    Camshaft Series: Drag Race
    Camshaft Type: Mechanical
    Grind Number: FF 294B-8
    Idle Quality: Rough
    Lifters Included: No
    Lobe Seperation Angle: 108
    Valve Lash Settings: .030 / .030
    Valve Lift (in.): .589 / .615


    You can probably go bigger but there is not enough information to make that call. You have to check your piston to valve clearance and your cam timing. If your cam timing is advanced or retarded then that will affect piston to valve clearance as well. Also, what is your compression ratio? A bigger cam might make your engine a dog if the CR is too low.
    Also how good are your heads? More lift might not do you any good if the heads flow max at .550, more duration would help if you have the compression to handle it.
    There are lots of factors to picking the right cam, make sure you gather as much info about the engine as possible.

    I'm guessing you have around 8:1 compression with those dished...oops, I mean "inverted dome" pistons lol. I would recommend less cam, something like 240 @ .050" lift, 106 LCA, .550" lift, 4 degrees advance.
    Last edited by moparmanjames; 07-10-2011 at 09:04 AM.

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    Quote Originally Posted by obnoxious001 View Post
    Better check out your tachometer. Sounds like it may have a setting for 4/6/8 cylinders, and it's on the 4 cylinder setting, not very likely that you are turning 8000 rpm.

    something tells me he is a bored regular having some fun.

    If not, he should answer the question about what rpm range we wants to run it in? 650hp at what rpm?

    He also needs to remember that bigger isn't always better. The cam specs posted aboe look to be very very good for that engine combo. As an example Comp Cams has a grind for Jet Boats that's 270/276 @ .050 and .649/.642 lift on a 108* lobe center its power range is 4000-7000. But the cam he has is better suited for for his pump gas 650 goal.

    " I have stock water cooled headers." are these logs or headers ?


    S CP
    Last edited by Sleeper CP; 07-10-2011 at 09:05 AM.

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    Ok I looked up your heads and they should have an 88cc combustion chamber, so it's looking like you might have anywhere from 8.5 to 9.5:1 depending on the dish volume, compression height, piston to deck clearance and head gasket thickness.

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    Quote Originally Posted by moparmanjames View Post
    Ok I looked up your heads and they should have an 88cc combustion chamber, so it's looking like you might have anywhere from 8.5 to 9.5:1 depending on the dish volume, compression height, piston to deck clearance and head gasket thickness.
    He could use a compression bump to 10:1 -10.5 to get the benifit out of that cam. 10:1 will do but at 8.5:1 -9:1 it's leaving a bunch on the table.

    Did he mention what size CARB ?


    S CP

    "Dark Sarcasm"
    Going fast is only half the fun ... what you make go
    fast is the other half.
    " A Government big enough to give you everything you want is big enough to take away everything you have"

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    Quote Originally Posted by Sleeper CP View Post
    He could use a compression bump to 10:1 -10.5 to get the benifit out of that cam. 10:1 will do but at 8.5:1 -9:1 it's leaving a bunch on the table.

    Did he mention what size CARB ?


    S CP
    looks like an 850dp

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    Senior Member hydroman916's Avatar
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    I have a 555ci big chevy, tunnel ram, 750 holleys, aluminum heads, it is a 9:1 motor, pump gas, made 762hp on the dyno, my cam is .777 .731 advertised duration 321 330, 288 290 at .050, and lobe lift .457 .430, lobe speration is 110
    get blown or get blown away

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    Quote Originally Posted by hydroman916 View Post
    I have a 555ci big chevy, tunnel ram, 750 holleys, aluminum heads, it is a 9:1 motor, pump gas, made 762hp on the dyno, my cam is .777 .731 advertised duration 321 330, 288 290 at .050, and lobe lift .457 .430, lobe speration is 110

    Curious are you recommending your cam for his engine combo?

    Your cam is bigger than the cam in my 565 that made 935 hp at 7,000 with a single 1,050. ( 12:1 comp)


    S CP
    Last edited by Sleeper CP; 07-10-2011 at 02:23 PM.

    "Dark Sarcasm"
    Going fast is only half the fun ... what you make go
    fast is the other half.
    " A Government big enough to give you everything you want is big enough to take away everything you have"

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    Quote Originally Posted by Sleeper CP View Post
    Curious are recommending your cam for his engine combo?

    Your cam is bigger than the cam in my 565 that made 935 hp at 7,000 with a single 1,050. ( 12:1 comp)


    S CP
    Sleeper, I don't think he has the heads to support anything bigger. It might be a bored member. Not enough info.

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