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  1. #1
    Registered Biggus's Avatar
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    What's a good cam upgrade for a 575SCI??

    I'n reading KAAMA's thread on cam selection, I'd like your opinions on a decent cam upgrade for the 575SCI.

    I never could understand why the Merc engineers chose a flat tappet cam for this motor over a nice roller set up.

    Anyone here tried the 741 in a 575SCI? Or, the same profile as the 500EFI?

    I do like the reliability of the stock GM roller lifters and dog bone retainers but I believe you are limited to a .600 lift with them.

    Kurt

  2. #2
    Platinum Member Platinum Member Dano's Avatar
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    Re: What's a good cam upgrade for a 575SCI??

    Good question...they moved to the roller in the new 600.

  3. #3
    Platinum Member Platinum Member Quiet Storm's Avatar
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    Re: What's a good cam upgrade for a 575SCI??

    I'm getting the cams in my 575's replaced with Crane custom ground hydraulic cams and using Morel hydraulic lifters.

    I'll try to get some #'s. The engine builder has specified how to grind it. I wouldn't have a clue.

    I'm not sure my #'s would help you anyway. My blocks had to be bored and the pistons replaced.

  4. #4
    MarineKinetics Commercial Member rmbuilder's Avatar
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    Re: What's a good cam upgrade for a 575SCI??

    Biggus,
    The factory Chevy lifters will accept up to .326" lobe or .560"-.570" valve with the stock base circle cam. Any more than that and you will need to upgrade to the retro-roller.
    Bob

  5. #5
    RLW
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    Re: What's a good cam upgrade for a 575SCI??

    The consensus seems to be that the 741 will fit in just about any 502 based engine regardless of CID.
    I find it hard to believe that such a cam exist that will do everything for everybody.
    Old School thinking to say the least.

  6. #6
    Registered Biggus's Avatar
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    Re: What's a good cam upgrade for a 575SCI??

    Anyone here running a hotter cam in a 575SCI?

    Quiet Storm, ours have been bored to 509" with flat top pistons. I'm very interested to hear about your cam selection.

    I absolutely hate running tie bar lifters. Are the tall body Crane lifters (dog bone style) a reliable choice?

  7. #7
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    Re: What's a good cam upgrade for a 575SCI??

    The crane replacements are a good choice. The problems you run into with the stock ones are as the cam gets larger in lift, the base circle gets smaller and the lifters then fall out of their guide bars. The lifters do NOT rise any farther as the lobe can only be as tall as the journals of the camshaft.

  8. #8
    Registered Canada Jeff's Avatar
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    Re: What's a good cam upgrade for a 575SCI??

    Quote Originally Posted by RichardCranium572
    The crane replacements are a good choice. The problems you run into with the stock ones are as the cam gets larger in lift, the base circle gets smaller and the lifters then fall out of their guide bars. The lifters do NOT rise any farther as the lobe can only be as tall as the journals of the camshaft.
    True, but the rest position can be lower.

    Before camming up the 575, wouldn't we want to install an intercooler?

    Innovation Marine I have heard does great work on the HP500EFI in terms of rebuild and netting like 600hp out of them, proven! In wounder if they have rebuild these and what the out come is? Does anyone have a link to they web site?

  9. #9
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    Re: What's a good cam upgrade for a 575SCI??

    For reference comparison, what are the original 575 cam specs for lift and duration?

  10. #10
    MarineKinetics Commercial Member rmbuilder's Avatar
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    Re: What's a good cam upgrade for a 575SCI??

    zahndok

    Crane single pattern
    Lobe H 240/329
    300/300 @.0042
    240/240 @ .050
    148/148 @ .200
    .559/.559
    105 ICL
    115 ECL
    110 LSA
    INTAKE 43 BTDC 77 ABDC
    EXHAUST 83 BBDC 37 ATDC
    Bob


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