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  1. #1
    Petty Officer 2nd Class madman2021's Avatar
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    Default high performance cam for 140/3.0???

    ive found on ebay about 3 or 4 different cams made by isky for the chevy 151 or 181. was wondering if these would be any good for better performance/gas milage/and rough idle with thru hull exhaust? has anyone used them before? good or no good? thoughts or opinions?

    thanks
    2008 southfork 18x60cc commercial series 01 yamaha 115 2 stroke
    1990 boston whaler 25 walkaround twin 225 yami ox66
    1990 boston whaler 25 walkaround twin 175 evinrude carb(work in progress)
    1989 wellcraft 250 sportsman(work in progress)
    1987 boston whaler 20 outrage 1997 Johnson 225 2 stroke
    (2) 2007 yamaha vx110 deluxes
    1989 Kawasaki 650sx
    1990 Kawasaki 849 x2
    2002 ford excursion diesel 4x4 412hp
    2001 ford ranger 4x4

  2. #2
    Fleet Admiral HT32BSX115's Avatar
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    Default Re: high performance cam for 140/3.0???

    Howdy,

    You already have a cam that's optimized for a marine application. Any other cam that increases the duration and/or might improve performance will also increase chances for reversion.

    If you want more performance, and unless you want to go to a "dry-stack", you'll need to get a bigger engine....


    Cheers,


    Rick
    73 de Rick
    ----------------------------------------------------------------------------------
    I use xxx oil and have never had a problem........
    1987 FourWinns 211 Liberator, 7.4L- Bravo III installed by ME,
    Formerly OMG 460 King Kobra powered
    1947 Stinson 108-2 Station Wagon
    , Franklin 6A-335B. Hartzell CS 2-blade prop
    -
    All PM's cheerfully answered! Please ask tech questions in the appropriate forum so everyone's included

  3. #3
    Moderator Bondo's Avatar
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    Default Re: high performance cam for 140/3.0???

    Ayuh,... What you're seeing are cams for Hot Rod Cars, with the Iron Duke motors...

    They are Very Different that the motors We use in Boats....
    For 1 thing, the distributer is in a Different spot....
    Any Grease is Better,..... Than No Grease at All.......

  4. #4
    Petty Officer 2nd Class madman2021's Avatar
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    Default Re: high performance cam for 140/3.0???

    the ad states there made for mercruiser 2.5 and 3.0
    2008 southfork 18x60cc commercial series 01 yamaha 115 2 stroke
    1990 boston whaler 25 walkaround twin 225 yami ox66
    1990 boston whaler 25 walkaround twin 175 evinrude carb(work in progress)
    1989 wellcraft 250 sportsman(work in progress)
    1987 boston whaler 20 outrage 1997 Johnson 225 2 stroke
    (2) 2007 yamaha vx110 deluxes
    1989 Kawasaki 650sx
    1990 Kawasaki 849 x2
    2002 ford excursion diesel 4x4 412hp
    2001 ford ranger 4x4

  5. #5
    Petty Officer 2nd Class madman2021's Avatar
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    Default Re: high performance cam for 140/3.0???

    2008 southfork 18x60cc commercial series 01 yamaha 115 2 stroke
    1990 boston whaler 25 walkaround twin 225 yami ox66
    1990 boston whaler 25 walkaround twin 175 evinrude carb(work in progress)
    1989 wellcraft 250 sportsman(work in progress)
    1987 boston whaler 20 outrage 1997 Johnson 225 2 stroke
    (2) 2007 yamaha vx110 deluxes
    1989 Kawasaki 650sx
    1990 Kawasaki 849 x2
    2002 ford excursion diesel 4x4 412hp
    2001 ford ranger 4x4

  6. #6
    Admiral ziggy's Avatar
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    Default Re: high performance cam for 140/3.0???

    to be blunt. give it up.
    i been reading these forums for a few years and the I4 and I6 have no mod's to make them anything more than they are. both are way durable engines, but they can never be made into something other than what they are. if ya want something ya can work with. get a 4.3 or a 5.7. these have possibilities for souping up some.
    thats imho from what i have read here for years. unless someone changes my mind, i believe it too.
    fwiw. i just keep my I6 in good tune. it'll never be a racer. but it sure makes for a great pleasure boat/ski boat/cruiser engine..... depending on the boat, yers will likely be similar (unless you boat is truly under powered).
    'Lime Time'
    1975 AristoCraft Nineteen
    Mercruiser 165hp (chevy 250 L6), MC-1 drive

  7. #7
    Rear Admiral Howard Sterndrive's Avatar
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    Default Re: high performance cam for 140/3.0???

    looks like maybe .030" more lift, but close to stock
    a marine/rv cam is what car folk call a "mild cam"
    which would be a peppy cam for the 62 Chevy II
    they aren't advertising it as anything other than that

    the price is ok - summit is cheaper

    edit: - just comparing this cam to stock - not sure it would be ok with stock springs at .510, but probably ok

    my concern is the 109 lobe separation.. looks like this is for some sort of flat track racing application more than marine

    the stock cam is 112 deg.

    the one Isky recommends for marine is also 112 deg
    part number 251256

  8. #8
    Petty Officer 2nd Class madman2021's Avatar
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    Default Re: high performance cam for 140/3.0???

    im not saying im trying to build a racer, im just looking to alternatives for a little more power. im quite satisfied now with the performance i have now. 47 mph with a 21P. not bad for a 4 banger. but it would be nice to have a rougher idle and better low end power when i have the 21P prop on it. 4-5 people struggles to plane, but once up it flys. i was thinking cam or smart tabs.
    2008 southfork 18x60cc commercial series 01 yamaha 115 2 stroke
    1990 boston whaler 25 walkaround twin 225 yami ox66
    1990 boston whaler 25 walkaround twin 175 evinrude carb(work in progress)
    1989 wellcraft 250 sportsman(work in progress)
    1987 boston whaler 20 outrage 1997 Johnson 225 2 stroke
    (2) 2007 yamaha vx110 deluxes
    1989 Kawasaki 650sx
    1990 Kawasaki 849 x2
    2002 ford excursion diesel 4x4 412hp
    2001 ford ranger 4x4

  9. #9
    Admiral ziggy's Avatar
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    Default Re: high performance cam for 140/3.0???

    im just looking to alternatives for a little more power
    that's just it. a little won't do ya. ya won't notice it. so why bother. what the oem provides is as good as it gets.
    im quite satisfied now with the performance i have now. 47 mph with a 21P. not bad for a 4 banger.
    outstanding. hows yer holeshot? top speed is to much though. sweet. my 165 L6 19' only does 41 or so. maybe 42 gps...
    but it would be nice to have a rougher idle and better low end power when i have the 21P prop on it. 4-5 people struggles to plane, but once up it flys. i was thinking cam or smart tabs.
    think v8, not mods to your I4...


    imho....
    'Lime Time'
    1975 AristoCraft Nineteen
    Mercruiser 165hp (chevy 250 L6), MC-1 drive

  10. #10
    Petty Officer 1st Class kilowatts's Avatar
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    Default Re: high performance cam for 140/3.0???

    Hi Guys:

    I'm with Ziggy. If you start installing items in a marine engine which are not really for marine use you will more than likely have problems. From your stats, no matter what you do I can't imagine your boat getting better performance than you have already. Maybe time for a bigger boat?

    kilowatts

  11. #11
    Petty Officer 2nd Class madman2021's Avatar
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    Default Re: high performance cam for 140/3.0???

    why does the top speed seem to high? the boat handles just fine. currently no trim tabs, hydrofoil, or finned anoide. getting around to 2 of those eventually.

    im thinking maybe a 75 shot of NOS will be nice =P lol.
    2008 southfork 18x60cc commercial series 01 yamaha 115 2 stroke
    1990 boston whaler 25 walkaround twin 225 yami ox66
    1990 boston whaler 25 walkaround twin 175 evinrude carb(work in progress)
    1989 wellcraft 250 sportsman(work in progress)
    1987 boston whaler 20 outrage 1997 Johnson 225 2 stroke
    (2) 2007 yamaha vx110 deluxes
    1989 Kawasaki 650sx
    1990 Kawasaki 849 x2
    2002 ford excursion diesel 4x4 412hp
    2001 ford ranger 4x4

  12. #12
    Petty Officer 1st Class
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    Default Re: high performance cam for 140/3.0???

    marine needs a wide L.S.A to prevent water reversion thats why the 112. 109 would be way to much valve overlap. in gen 1 small blocks 480 lift is as high as you can go without screw in studs and guide plates.the purple strip z-28 valve springs were good for 480 lift but to go 510 lift you needed something better.and the specs on that cam are way past rv cam.go to comp cam and check it out. i ported my 140 head [should say cleaned it up] had a 3angle valve grind and i noticed improvement.

  13. #13
    Lieutenant dockwrecker's Avatar
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    Default Re: high performance cam for 140/3.0???

    Smart tab it at most and leave it alone. That should satisfy your wing urges. Slap on an STP sticker or maybe a Mallory one. Next get a CD with drag racing noises on it and play it at the docks for the babes. They'll dig it..
    But seriously what you're getting out of that thing is pretty much all there is, and it sounds like it's doing a good job. Enjoy it. With Smart Tabs. And babes...vrooom!
    90 Carver Montego 21.5 (23') "Lady Minna" (yes a name change in honor of our fallen Labrador. Poseidon understands.)

    In the immortal words of Hunter S. Thompson:
    "Life should not be a journey to the grave with the intention of
    arriving safely in a pretty and well preserved body, but rather to skid
    in broadside in a cloud of smoke, thoroughly used up, totally worn out,
    and loudly proclaiming "Wow! What a Ride!"

  14. #14
    Moderator Bondo's Avatar
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    Default Re: high performance cam for 140/3.0???

    but it would be nice to have a rougher idle and better low end power
    Ayuh,... A rough idle equates to pizzpoor docking...'n there's No low end power with that cam...
    It states it's a 2000 rpm to 6000 rpm cam...
    The cam don't make More power, it just moves the same power, Farther up the rpm band...
    Putting that cam in yer motor, it'll Never even get onto plane...

    Either be Happy with what you've got,...
    Or,...
    Buy a boat with a Bigger Motor...
    Any Grease is Better,..... Than No Grease at All.......

  15. #15
    Petty Officer 1st Class
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    Default Re: high performance cam for 140/3.0???

    Porting and polishing adds some hp but then the log exhaust makes it all undone.
    Good luck!

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