Jet Boat cam
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Jet Boat cam

  1. #1
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    Default Jet Boat cam

    Any Recommendations?

    Pump is a fresh JC split bowl pump, tight clearances, with a Berk A impeller

    Don't have too much of motor specs right now. The motor is a 454 .030" over, Tunnel Ram, and dual 450dp's on top. Should be around 10:1 compression.

    The heads are professionally ported 427 Rectangle, closed chamber heads, ported by Geoff Mummert. Not sure on the valves yet, won't get them until tuesday next week... but I'm sure they are on the larger side

    I would like to turn this A impeller 5600Rpm, or at least according to the extended impeller chart. I was looking forward to Flowing the heads again and having a solid roller cut..... don't have the funds right now but definetly going to be doing it in the future.

    Instead I would like to run a solid cam for right now. I'm not sure on the Piston to valve clearance and how big I can go, haven't quite measure it yet.... but I would like something around .600 for safety.

    I guess that's as vague as I can get lol. I got an idea of the lift I want to run, just not quite sure on the duration, seperation, centerline, etc...

    Advice?

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    Senior Member HKROB's Avatar
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    Quote Originally Posted by Pw_Tony View Post
    Any Recommendations?

    Pump is a fresh JC split bowl pump, tight clearances, with a Berk A impeller

    Don't have too much of motor specs right now. The motor is a 454 .030" over, Tunnel Ram, and dual 450dp's on top. Should be around 10:1 compression.

    The heads are professionally ported 427 Rectangle, closed chamber heads, ported by Geoff Mummert. Not sure on the valves yet, won't get them until tuesday next week... but I'm sure they are on the larger side

    I would like to turn this A impeller 5600Rpm, or at least according to the extended impeller chart. I was looking forward to Flowing the heads again and having a solid roller cut..... don't have the funds right now but definetly going to be doing it in the future.

    Instead I would like to run a solid cam for right now. I'm not sure on the Piston to valve clearance and how big I can go, haven't quite measure it yet.... but I would like something around .600 for safety.

    I guess that's as vague as I can get lol. I got an idea of the lift I want to run, just not quite sure on the duration, seperation, centerline, etc...

    Advice?
    Comp cams 280s magnum

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    Senior Member HKROB's Avatar
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    Boats N Hoes Brad22CP's Avatar
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    We've taken a lot of the guess work out for you here feel free to call our tech department for confirmation. Good Luck.

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    Quote Originally Posted by Brad22CP View Post
    We've taken a lot of the guess work out for you here feel free to call our tech department for confirmation. Good Luck.

    Brad, are these two cams hydraulic or solid?
    295-112444

    295-112444CL

  8. #6
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    Schneider Cams makes 4 jet boat specific cams and they can custom grind cams without any problems. They're in San Diego.

    The Comp Cams 280 is also a great cam, everything else right should put it around 500 HP.

  9. #7
    Resident Ford Nut Sleeper CP's Avatar
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    Tony, I'd be more apt to use a cam with a 108 lobe sep. It will help the upper mid range it will idle a bit rougher but I'd take that to get the extra pop.

    It would be great if you could split the difference beween the 280S and 294B
    the 280 is 242/250 @ .050 with .575/.604 lift with a lobe sep of 110 and the 294 has 256/266 @ .050 .580/.605 lift with a 108 lobe sep.

    Take the lift and lobe sep of the 294B and cut the dur to 248 int. and 258-260 on the ex. I think it would do well to 6,400 but it will pull very hard above 5,000.

    Just my 02.

    Ask Geoff when you talk to him about the heads.

    Sleeper CP

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    fast is the other half.
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  10. #8
    Senior Member ol guy's Avatar
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    Quote Originally Posted by Pw_Tony View Post
    Any Recommendations?

    Pump is a fresh JC split bowl pump, tight clearances, with a Berk A impeller

    Don't have too much of motor specs right now. The motor is a 454 .030" over, Tunnel Ram, and dual 450dp's on top. Should be around 10:1 compression.

    The heads are professionally ported 427 Rectangle, closed chamber heads, ported by Geoff Mummert. Not sure on the valves yet, won't get them until tuesday next week... but I'm sure they are on the larger side

    I would like to turn this A impeller 5600Rpm, or at least according to the extended impeller chart. I was looking forward to Flowing the heads again and having a solid roller cut..... don't have the funds right now but definetly going to be doing it in the future.

    Instead I would like to run a solid cam for right now. I'm not sure on the Piston to valve clearance and how big I can go, haven't quite measure it yet.... but I would like something around .600 for safety.

    I guess that's as vague as I can get lol. I got an idea of the lift I want to run, just not quite sure on the duration, seperation, centerline, etc...

    Advice?
    Advice is free. #1 don't over cam the boat. If you want to idle and not kill plugs all day then kick it down a notch.solid lifter cams are great,they create more bottom end than a hyd deal. If you want loappity loap go ahead and run a short lobe center but plan on alot of tune time and dont think about an idle below 1k. IMO 525 to 530 on the intake and 550 on the exhaust for lift. Duration @ .050 I would go 218 to 235 intake and 225 to 235 exhaust with a 110 lobe center. BIGGER BETTER idea call Chet Herbert in china Ca and ask him. If Chet is not available ask for Donny Johannson. These guys have been building motors and grinding cams longer than most of us have been driving.Again IMO. They are all I will use on cams and for thirty years have never let me down. Valve springs are the next hill to climb, You want 5600 rpm then a seat pressure of 150 lbs and open valve at 280 to 320 lbs. M

  11. #9
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    Quote Originally Posted by ol guy View Post
    IMO 525 to 530 on the intake and 550 on the exhaust for lift. Duration @ .050 I would go 218 to 235 intake and 225 to 235 exhaust with a 110 lobe center. M
    Damn, it's going in the boat not in a Suburban that tow's it!!

  12. #10
    B1 Racing cs19's Avatar
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    Quote Originally Posted by Warp Speed View Post
    Damn, it's going in the boat not in a Suburban that tow's it!!
    LOL
    B1Racing.net

  13. #11
    Boats N Hoes Brad22CP's Avatar
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    Quote Originally Posted by Pw_Tony View Post
    Brad, are these two cams hydraulic or solid?
    295-112444

    295-112444CL
    Extreme Marine Hydraulic Flat Tappet XM288H
    Last edited by Brad22CP; 07-19-2008 at 10:39 AM.

  14. #12
    Senior Member lilrick's Avatar
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    my 10:1 has an Isky Z-45 and that is a flat tappet solid. I ran this combo in the pink hornet in nostalgia jet. Now, that same motor is in my 20' spectra v-drive cruiser. Love it. Get rid of the dual carbs and t-ram. Single 850 with an edelbrock performer air gap.

  15. #13
    Senior Member lilrick's Avatar
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    that's alot of cylinder head IMO. Not enough CR or cubic inch for the rpm intended. I would like to see you use an oval port head such as a 781 0r 049, but then that drops your cr with the piston combo you're using. Hmm. If you could find a set of CC ovals, that would be your best bet.

  16. #14
    steelcomp was here
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    Quote Originally Posted by Warp Speed View Post
    Damn, it's going in the boat not in a Suburban that tow's it!!
    Nice...cracked me up... (was thinking the same thing)
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.

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