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  1. #1
    Cadet
    Join Date
    Jul 2011
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    1

    Question 1992 Marada OMC 5.0 Cobra info/question(s)?

    I just purchased a 1992 21' Marada cuddy with OMC 5.0 Cobra engine. It is in great condition physically and seems to be in good condition mechanically, as it does run good. From a cold start, it does sometimes try to quit if not allowed to warm up for a few minutes first, but I was told that is normal for a carbureted engine.

    I haven't really been able to find any reviews on this boat and/or engine. I've read various group postings and a couple of them worried me such as "go with volvo engines, run away from anything OMC" but there was no explanation of that. Just wondering about other peoples experience with them, they tend to be a good engine? What are common problems that I should look out for?

    I have noticed when putting into gear from neutral there is a sort of grinding sound. It sounds bad, but hasn't given me any trouble so far. Any ideas?

    Additionally I am wondering what I should expect from this boat as far as speed. Everything is stock and right now with only one average size person and less than 10 pounds of cargo on calm water I get get up to around 45mph. Considering the size of the engine I expected faster, as other small fishing boats with smaller engines zip past me all the time. I also notice the RPMs never seem to go above 3000rpm even with the throttle all the way down. I'm wondering is it possible to tune this? I imagine it would go quite a bit faster if I were able to get the RPMs up to 4000-4500, I guess maybe an adjustment in the throttle cable?

    Any input/info is greatly appreciated!

  2. #2

    Question Re: 1992 Marada OMC 5.0 Cobra info/question(s)?

    Quote Originally Posted by mwhii View Post
    I just purchased a 1992 21' Marada cuddy with OMC 5.0 Cobra engine. It is in great condition physically and seems to be in good condition mechanically, as it does run good. From a cold start, it does sometimes try to quit if not allowed to warm up for a few minutes first, but I was told that is normal for a carbureted engine.

    I haven't really been able to find any reviews on this boat and/or engine. I've read various group postings and a couple of them worried me such as "go with volvo engines, run away from anything OMC" but there was no explanation of that. Just wondering about other peoples experience with them, they tend to be a good engine? What are common problems that I should look out for?

    I have noticed when putting into gear from neutral there is a sort of grinding sound. It sounds bad, but hasn't given me any trouble so far. Any ideas?

    Additionally I am wondering what I should expect from this boat as far as speed. Everything is stock and right now with only one average size person and less than 10 pounds of cargo on calm water I get get up to around 45mph. Considering the size of the engine I expected faster, as other small fishing boats with smaller engines zip past me all the time. I also notice the RPMs never seem to go above 3000rpm even with the throttle all the way down. I'm wondering is it possible to tune this? I imagine it would go quite a bit faster if I were able to get the RPMs up to 4000-4500, I guess maybe an adjustment in the throttle cable?

    Any input/info is greatly appreciated!
    I have the same motor as you do, but my boat is a Fourwinns.....I also have the same issue, my RPM's never go past 3000 with my throttle down all the way....I've tried to adjust the throttle shifter cable but can't figure it out.....let me know when you find out what the issue was.....

  3. #3
    Lieutenant airdvr1227's Avatar
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    Jul 2009
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    Massillon & Marblehead Ohio
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    Default Re: 1992 Marada OMC 5.0 Cobra info/question(s)?

    I think you might be getting mis information from your tach. A 21 ft cuddy at 45 mph should be more than 3,000 rpms, and 45 mph is about all you should expect from your setup.

    http://forums.iboats.com/mercruiser-i-o-inboard-engines-outdrives/list-possible-causes-low-wot-295070.html

    This link points you in the direction of possible causes of your problems, but the first thing I would do would be to verify your tach reading. I think you might find that your tach is wrong.

    SOme gear grinding is normal when engaging the drive. Big time clunking is not. The reason people are so down on OMC is they went out of business a while back and 1) parts are getting difficult to find 2) when you find them they are getting expensive and finally 3) it's getting difficult to find qualified mechanics to work on the drives.


    I tried to contain myself...but I escaped!

    Scott & Roxanne
    1989 Carver Santego 30
    Twin Merc 5.7L Alphas

  4. #4
    Fleet Admiral HT32BSX115's Avatar
    Join Date
    Dec 2005
    Location
    WA
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    7,803

    Default Re: 1992 Marada OMC 5.0 Cobra info/question(s)?

    I haven't really been able to find any reviews on this boat and/or engine. I've read various group postings and a couple of them worried me such as "go with volvo engines, run away from anything OMC" but there was no explanation of that. Just wondering about other peoples experience with them, they tend to be a good engine?
    Howdy,

    Welcome Aboard!

    Well, to the first question, it's probably a moot point since you already bought it!

    In a nutshell, OMC went out of business more than 10 years ago. depending on what's wrong and the parts you need, some are not available........So if you had asked here on this forum, several people would have told you to "run away" and would have given you many specific reasons.

    You also have the FORD 5.0L engine. .........Sterndrive manufacturers abandoned Ford Marine back in the 90's........not a lot wrong with Ford but Mercury and Volvo went with GM........the result of that is that the exhaust manifolds and risers and maybe some other parts like ignition stuff, might be more scarce might be a little more $$ to buy........... Sorry about that!


    No matter. You have it now. It's not the end of the world either!

    There's a some bad things and some "good" things.


    The good thing is that you can still get most of the parts for a dog-clutch Cobra (which you have) I am not sure about the ignition system. It's possible that your dist and the module is not available but you can buy an aftermarket distributor if it breaks and you cannot fix what you have.

    You can also replace the drive with a "kit" from SEI that allows you to put an adapter and their excellent "Alpha" drive on the back of a Dog-clutch Cobra gimbal. I'm not suggesting that you do this but you have that option if your drive "goes" in the future.

    For both of you guys here, check out MUST HAVE Technical Information for DIYers.

    Look at all of it, but scroll down to #13 for possible problems with WOT RPM.

    If the drive is "clunking" once it's in gear DO NOT operate it that way or you WILL destroy the drive. You have a possible defective lower shift cable or it's out of adjustment.

    Also have a look at http://www.hastings.org/~stuart/cobra/


    Regards,


    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

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