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Thread: Motor Mess

  1. #1
    Powerquestboy
    So I have a friend who drives a 98 Moomba Ski boat. The boat has a Vortec 350 in it. He blew the impeller and for some unknown reason decided the best way to fix it would be to rev the motor up and drive as fast as possible. Now as you would expect he has a cracked head and block. Anybody know of a cheap longblock out there for sale. He would buy a whole motor if the price was right. He wants to put the exact same engine back in it. Another problem is he has a bunch of rednecks working on it. I need to know if there is any difference between the marine and street version of this motor he should know about. They think it is exactly the same and are going to buy a block for a car, I’m no mechanic so I want to know the differences between the street and marine application if any. Thanks for the help.

  2. #2
    rrrr
    Sounds like he's in the process of making Big Mistake #2. He needs to get a marine mechanic now, cause otherwise he'll be finding one later.
    Marine engines are built with different clearance specifications than car engines.

  3. #3
    not guilty
    DIFFERENCES ,NAH PRETTY MUCH EXACT , WELL AHHH EXCEPT FOT THE CAM AND VALVES & SPRINGS AND ER-AH PISTONS AND WELL , YEAH THEY DO USE THE SAME BLOCK !
    GET THE REDNECKS OUT OF THE BOAT NOW OR YOU'LL ALL BE TRYING TO SKI BEHIND THE TRAILER ! NG

  4. #4
    Unchained
    As I read it, the problem was'nt car vs. marine engine. It was driving with a bad water pump. Same damage as if you drove a car with a bad water pump and there was no cooling.
    Go get a new 350HO crate engine.

  5. #5
    Powerquestboy
    Well it turns out the heads are ok and he found a block for $500. The problem is its bored 40 over so he has to buy new pistons and rings. Everything else they are using is off his old engine so it should be correct for a marine application. Can anyone tell me what kind of pistons not to use? or do you think it will be ok. I tried to get him to take it to a marine mechanic but he wont, he wants to fix it cheap and sell it. The ol make it someones elses problem! The only reason I'm trying to help him is because I always have to tow him in and it ruins my day. I think I'll buy him an oar. Thanks for the info

  6. #6
    jstwkd
    The only diff should be head gaskets. I installed a crate motor in a ski boat with no problems.The gaskets just wont work well in salt water.
    The same thing happedned to this guy.
    Also you need to now if it has a right hand / or left hand rotation motor.You can find the motor rotation on the air cleaner it should say Rh or Lh.Left hand rotation is a normal rotating motor. Same as the crate motor.You shouldnt need to make any changes. If it is a Right hand rotation motor than you will need to install the correct cam. The gears will be cut different for the dist.

  7. #7
    gnarley
    [QUOTE]Originally posted by not guilty:
    DIFFERENCES ,NAH PRETTY MUCH EXACT , WELL AHHH EXCEPT FOT THE CAM AND VALVES & SPRINGS AND ER-AH PISTONS AND WELL , YEAH THEY DO USE THE SAME BLOCK !
    WHAT HE SAID, you'd be surprised what is different. MY advice, look on the motor & find out who did the marinizing to it & call them with the serial #! I have found many part #'s are NOT listed at GM & only the marinizing company like Mercury will have that info if at all! If it is a GM Vortech Marine unit they should be able to tell you what is different, like the intake manifold that has the bronze insert in it for corrosion prevention, & the cam that may be different because the boat has different power needs & on & on.

  8. #8
    not guilty
    If youre going to have all original parts (cam,heads,rods,crank etc)you can get by with a set of speed pro hypereutectic pistons.I've used them in several as a stock marine flat top forged replacement(at about half the cost) with no problems.
    Also invest in a couple of felpro marine head gaskets seperate instead of trying to buy a cheap overhaul gasket set.good luck NG

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