Small Block in a CVX-20 conversion?
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Small Block in a CVX-20 conversion?

  1. #1
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    Default Small Block in a CVX-20 conversion?

    I have a small block Chevy that I had pulled out of my old hot rod.
    355 @ 9.8:1 w/ 2.02 / 1.60 ported double hump heads, Cam @ 224 dur @.050 & 450/460 lift, etc... Rated @ 377hp @ 5500 rpm & 395ft/lbs @ 4500 rpm
    Might have found a good deal on a CVX-20 that has a cracked block 460 / Berkley pump.

    I know a small block is not the 'norm' for a jet but really interested in using this mouse.
    - What's involved in changing the bell housing / motor mounts for a small block Chevy with a Berkeley that is currently set w/ a BB Ford?
    - Best source for getting new bell housing motor mounts?
    - I currently have a set of new Osco center riser exhaust manifolds I'm hoping I can use.

    Thoughts on installing a Chevy small block in place of the 460 Ford?

    Thanks,
    Steve
    Last edited by CZSteve; 02-24-2012 at 08:47 AM.

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  3. #2
    Senior Member jetboatperformance's Avatar
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    Quote Originally Posted by CZSteve View Post
    I have a small block Chevy that I had pulled out of my old hot rod.
    355 @ 9.8:1 w/ 2.02 / 1.60 ported double hump heads, Cam @ 290 dur / 450 lift, etc... Rated @ 377hp @ 5500 rpm & 395ft/lbs @ 4500 rpm
    Might have found a good deal on a CVX-20 that has a cracked block 460 / Berkley pump.

    I know a small block is not the 'norm' for a jet but really interested in using this mouse.
    - What's involved in changing the bell housing / motor mounts for a small block Chevy with a Berkley that is currently set w/ a BB Ford?
    - Best source for getting new bell housing motor mounts?
    - I currently have a set of new Osco center riser exhaust manifolds I'm hoping I can use.

    Thoughts on installing a Chevy small block in place of the 460 Ford?

    Thanks,
    Steve
    A CVX 20 is really a 18'+ hull BTW and although it may bit under powered it should perform OK ,that hull might not "like" the loss of weight in the ass end , mounts, bell hsg etc and all else to rig it are readily available (some BBC parts will work depending on year model) You'll likley want to change impellers to work with the smaller CU , Your OSCOs will work but weigh a ton (if iron), Gotta hunch based on your posted cam specs that your cam duration @ 50 exceeds 240* if so the cam could cause water reversion issues when using thru hull exausts Tom

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    Sorry, cam duration @ .050 is 224 (SAE is 291).

    Cam specs:
    .050 Dur Intake: 224 Exhaust: 224
    Cam Lift Intake: .300 Exhaust: .307
    Valve Lift Intake: .450 Exhaust: .460
    Lobe Ctrs 114 for both

    Motor is set to be hooked up into a 77 Sea Ray SRV-197 with a stock Alpha; having second thoughts about this motor and blowing up this outdrive.
    I've always loved the Carlson and like the idea of not having to worry about this motor being too much for the jet drive.

    Thoughts on this cam if I do this?

    EDIT: Yes, the exhaust manifolds are cast iron. I would think this the added manifold weight would help with the lighter weight of the small block compared to the originally spec'd big block.
    Last edited by CZSteve; 02-23-2012 at 08:30 PM.

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  6. #4
    Senior Member jetboatperformance's Avatar
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    Quote Originally Posted by CZSteve View Post
    Sorry, cam duration @ .050 is 224 (SAE is 291).

    Cam specs:
    .050 Dur Intake: 224 Exhaust: 224
    Cam Lift Intake: .300 Exhaust: .307
    Valve Lift Intake: .450 Exhaust: .460
    Lobe Ctrs 114 for both

    Motor is set to be hooked up into a 77 Sea Ray SRV-197 with a stock Alpha; having second thoughts about this motor and blowing up this outdrive.
    I've always loved the Carlson and like the idea of not having to worry about this motor being too much for the jet drive.

    Thoughts on this cam if I do this?

    EDIT: Yes, the exhaust manifolds are cast iron. I would think this the added manifold weight would help with the lighter weight of the small block compared to the originally spec'd big block.
    The cam should work (re reversion) and you may have a point with the manifolds (weight) We own two of these boats , have always liked them Tom

  7. #5
    Senior Member Mash on It's Avatar
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    My mostly stock sbc pulls an 'A' impeller to 46-4700 rpm, the previous motor, 460 ford only pulled 4400, (same pump) and the sbc weighs 200-300 lbs less. Saving weight can always be added with coolers, gear, etc.

    My $0.02

    Daniel
    Mash on it
    "Never mind the mule, Just load the wagon"
    '76 Eliminator 21'

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