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  1. #1
    Cadet
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    Default Replacing Chevy 350 engine suggestions?

    It looks like we have to replace the 350 engine in my sonís 22ft BW Revenge. We can buy a brand new Chevy 350 with 4 bolt main, 2 pc rear seal engine for $1563.00 in stock locally. All the other things should fit on this engine since it is the same as the old one, we hope. This, of course, is not a marine engine, thus no warranty.

    What if we were to replace the seals and gaskets ( especially head ), the cam, and freeze plugs? All the other parts, like carb, fuel pump, starter, alt, are marine. What do you think about this approach to solving our re-power dilemma?

    The boat is used about 3-4 times a month from April to September for fishing in brackish water, and usually not run continually, except for trolling for 6 weeks in the spring.

    Are we to be concerned about longevity, or cracking a piston, throwing a rod, or other internal engine damage?
    Your input will be greatly appreciated. Thanks!

  2. #2
    Moderator Bondo's Avatar
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    Default Re: Replacing Chevy 350 engine suggestions?

    We can buy a brand new Chevy 350 with 4 bolt main, 2 pc rear seal engine for $1563.00 in stock locally.
    Ayuh,....

    You can pretty much just dress that truck motor with the Merc. components from your take-out motor,+ Go Boatin'...

    Last I knew the GM crate motors are spec.ed for trucks,+ have composite headgaskets,+ brass coreplugs...
    The Cam,+ other internal components are a Non-issue...
    Any Grease is Better,..... Than No Grease at All.......

  3. #3
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    Default Re: Replacing Chevy 350 engine suggestions?

    Thats a good price also, yep it's doable. And the easiest way to go.

    How old are the manifolds and risers another 500 bucks you can have new ones
    with gaskets and everything ready to install. All in one box, something you should consider.

    Good luck !

  4. #4
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    Default Re: Replacing Chevy 350 engine suggestions?

    Cant beat a new engine from gm for reman prices. They probably wont honor the warranty though.
    88 Larson Citation DC 175
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  5. #5
    Lieutenant Junior Grade slasmith1's Avatar
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    Default Re: Replacing Chevy 350 engine suggestions?

    If most or all of your boating is in brackish or salt now is also the time to add a fresh water cooling system (heat exchanger)
    Thats like wiping your butt before you go. You can do it, but it just don't make any sense.

  6. #6
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    Default Re: Replacing Chevy 350 engine suggestions?

    I will echo what he said.

    Heat exchanger based cooling is definitly the way to go. Protect your engine from corosion and potential freezing. Let your exchanger take all the risk and abuse.

  7. #7
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    Default Re: Replacing Chevy 350 engine suggestions?

    My boat is 23 years old saltwater used, still the same original manifold. Has a 22 year old saltwater used motor in it, If you flush every time you come off the water no reason why your new motor won't last that long.

    Point is i don't have the heat exchanger, a lot of boats don't have it.

    Why the old motor coming out may i ask, freeze damage??

    Really to many things go wrong with those fresh water heat exchangers, and they clog. They leak, i don't like them.

    Do a search for yourself on this forum make up your own mind.

    Good luck !

  8. #8
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    Default Re: Replacing Chevy 350 engine suggestions?

    I tend to like closed cooling systems even in freshwater. With a heat exchanger you can run the engine at a more efficient hotter temp. 180 vs 160 . In addition its pressurized which increases the boil over temp.
    If you get a kit that includes the manifolds in the system they will last for the life of the engine.
    Instead of running corrosive sea water though your expensive engine you run it though a nickel-copper heat exchanger which is naturally corrosion resistant and anti marine growth.
    I have never had any trouble with any of mine clogging up, but your in an area with more marine growth. (over 1500hrs done nothing to the cooling system,other than impellers)
    I'm just bias against raw water coolings systems i have had nothing but trouble with them.
    88 Larson Citation DC 175
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  9. #9
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    Default Re: Replacing Chevy 350 engine suggestions?

    In fresh water nobody needs a heat exchanger, period the boat will last longer then the owner.

    Saltwater is the where it would be needed and thats the debate.

    Just my 2 cents.

  10. #10
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    Default Re: Replacing Chevy 350 engine suggestions?

    Quote Originally Posted by chiefalen View Post
    In fresh water nobody needs a heat exchanger, period the boat will last longer then the owner.

    Saltwater is the where it would be needed and thats the debate.

    Just my 2 cents.
    Were i boat its silty so it keeps it out of the block and manifolds, cuts down on corrosion even in freshwater and makes winterizing a breeze. Everyone is has there own opinion though.
    88 Larson Citation DC 175
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  11. #11
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    Default Re: Replacing Chevy 350 engine suggestions?

    Abj is 100 percent correct, you have valid points and people do use the heat exchanger.

  12. #12
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    Smile Re: Replacing Chevy 350 engine suggestions?

    hi there this mean a 350 marine engine is the same as a automotive engine thanks.

  13. #13
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    Default Re: Replacing Chevy 350 engine suggestions?

    Heat exchangers take less time to flush aswell...

    IF you have a heat exchanger, you connect your muff's turn on your water, start your engine, let it idle for 30 seconds and your done.

    If you don't have a heat exchanger, you have to wait until your engine reaches 160 degrees for your theromstat to open, otherwise the water won't actually be circulating through the block.

    I know this isn't really that big of a deal, but it's the difference bettween letting your engine run for 30 seconds at the end of the day or 5-10 minutes.

  14. #14
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    Default Re: Replacing Chevy 350 engine suggestions?

    beta have you been reading the thread??

  15. #15
    Moderator Bondo's Avatar
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    Default Re: Replacing Chevy 350 engine suggestions?

    Quote Originally Posted by betayv View Post
    hi there this mean a 350 marine engine is the same as a automotive engine thanks.
    Ayuh,... Where does it say that Anywhere in this thread,..??
    Any Grease is Better,..... Than No Grease at All.......

  16. #16
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    Default Re: Replacing Chevy 350 engine suggestions?

    Thank you all very much for your input. I think the issue of whether to replace the raw water manifolds and risers, or switch to fresh water exchanger will come later.

    The reason to replace the engine is a long story. The boat was purchased knowing that the engine was very questionable. It is mainly centered around the fact that the cylinder bores are pitted, and the engine has already been rebuilt by previous owner.

    The main issue was whether this new Chevy truck engine can be used in a boat without any serious problems, if we use all the marine parts from the old engine.. Thank you Bond-o for your opinion. So, you think it will be just fine?

  17. #17
    Fleet Admiral Faztbullet's Avatar
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    Default Re: Replacing Chevy 350 engine suggestions?

    Here we go again, these threads are as bad as the 2 cycle oil threads I myself always install a marine spec engine as being taught thru Mercruiser service school there are MAJOR differences between auto/truck spec's and marine. Also the engines I install come with a 2 year warranty and will pay you $50.00 hr up to $550.00 for failure or problems with engine(none so far). I also have seen the Autozone/Napa/Carquest and Gm crate engine state no warranty if used in marine applacations. Do what you want this is just my opinion
    When in doubt,Trim it out!!!
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  18. #18
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    Smile Re: Replacing Chevy 350 engine suggestions?

    I agree with Faztbullet but someone can explain to me and Im sorry for being ignorant but internally the marine engine will be the same as automotive thanks.

  19. #19
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: Replacing Chevy 350 engine suggestions?

    betayv
    If you have a question, start a new thread about it. Don't hijack someone elses question with things you don't understand.
    You can use this one as a reference, to your question, but asking in this thread is just plain confusing to everyone trying to figure out who is answering which post.
    Don S.


    Please, no PM's (Private Messages) regarding boat/engine problems.
    That is what the forums are for.
    Only forum/moderator issues will be answered in PM's.

  20. #20
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    Smile Re: Replacing Chevy 350 engine suggestions?

    Im sorry thanks.

  21. #21
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    Default Re: Replacing Chevy 350 engine suggestions?

    Ok here we go, 1563 for a brand new crate motor straight from the dealer local to him.

    I will post a link at the end, 2700 for a brand new motor merc. Shipping 300 maybe more maybe less.

    Now lets explore the difference and the origin of both motors.

    Both gm, both off the same assembly line, one goes to merc one goes to the dealer.

    One costs more, bet you can guess which one.

    Surprise the merc one.

    Both the same, power curve, hp.

    Oh yea you get a 2 year warranty, from merc.??

    They gonna warranty a diy shade tree mechanic ,who installed himself it's merc motor ??

    There it is, bet others will chime in.

    http://www.michiganmotorz.com/Marine...marine+engines

  22. #22
    Fleet Admiral Faztbullet's Avatar
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    Default Re: Replacing Chevy 350 engine suggestions?

    I doubt they come off same assembly line as GM has their on marine division for these engines and the auto does not come with the bolt on windage tray, it built in on oil pan, has sodium filled valves vs S/S. This is off the the GM website so if the parts are the same why do they say they are not?

    "The same engine that powers your GM truck or SUV is specialized to create the unparalleled performance you can expect in a GM marine engine.
    GM Powertrain has designed a number of important features into its marine engines, such as corrosion resistant alloys, engine oil sealing system, marine-specific camshaft designs for some applications, and cooling systems that are compatible with both salt and fresh water environments."

    Because GM Powertrain knows the tremendous demand put on engines in the marine environment, GM marine engines are tested tough by being run at extensive wide-open throttle conditions, under load, when subject to the Marine GED test Schedule (Global Engine Durability)
    http://www.gm.com/experience/technol...ne_engines.jsp

    Also I use Grooms engines that sells to the public thru dealers with 2 year warranty on marine and lifetime on auto/truck. I have a reputation to stand by and have replaced to many "yea it will work" & "its the same" engines. I will not install a customer supplied engine(unless marine) or hook it but will align it for em . Customer is asking for advise and opinion and this is what I am supplying. Customer can do as he wishes as its his wallet.
    When in doubt,Trim it out!!!
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    14 x 48 Drifter with 1100SS Merc

  23. #23
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    Default Re: Replacing Chevy 350 engine suggestions?

    Fazrbullet, you are correct for wanting to cover your 6 for not wanting to install anything but a marine motor that you sold the customer. You deserve the markup for selling the motor, and ever penny for the labor to install it. Your knowledge and expertize, should be paid for.

    And your reputation is important to maintain.

    But this gentleman is buying and installing the motor himself. And when dressed with the" MARINE " water pump, starter, alternator, and fuel pump, off his old motor will perform just as well as a merc motor. And will be safe and will cost half.

    And the choice is his to make, with the proper information in hand.

    Good luck original poster !

  24. #24
    Moderator Bondo's Avatar
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    Default Re: Replacing Chevy 350 engine suggestions?

    Thank you Bond-o for your opinion. So, you think it will be just fine?
    Ayuh,...

    All the GM, Truck crate motors I've been able to get My fingers onto in the last 5 years or so,...
    Have All had the brass coreplugs,+ Composite headgaskets, as I stated before....
    Truck/ RV rated Cams, are cut So closely to a Marine cut,... There's virtually No Difference....

    Personally,... I wouldn't hesitate a Second about using a GM Truck crate motor in a Boat....
    Matter of fact,.. The organization I'm involoved with, has several installed in boats Now....
    All with Excellent service records,+ All still Running...
    Any Grease is Better,..... Than No Grease at All.......

  25. #25
    Fleet Admiral Faztbullet's Avatar
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    Default Re: Replacing Chevy 350 engine suggestions?

    I see it this way, I buy your boat and you tell me it had a new engine installed I think GREAT!!. I use it for several months and rawhide it one day and motor starts making noise. Being not "wrench friendly" I take to dealer, describe problem and tell em it has new engine. Tech looks/removes engine, and calls me telling me it not a marine engine. (1) He is a dealer(2) Tech has training to tell the difference(3) Has Mercury and Gm to back em up on marinizing engine details. Now I feel that I have been"screwed" and being the anal person that I am, you are going to get a NASTY phone call from me and a lawyer to meet later in a small claims court. I want the $$ for the repair to replace motor with proper marine engine per dealer & mercury/omc/volvo/ and refund on purchase price as boat value was lower than "book" because it did not have OEM or compairable item.
    I have: dealer/Mercury to back me up, GM's website,Gm's brochure that states not for marine use, aftermarket engine builders that build to marine spec's
    You have: Fellow on internet said it would work
    Who win"s???......................... Write me a check
    When in doubt,Trim it out!!!
    Business Owner & Certifed Technician
    Boats I own & use
    20ft Javlin w/250 Junkrude
    17ft Bullet w/200 Merc (SOLD!!)
    13ft Allison w/150 I-6
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    15ft Allison w/75 Stinger(project)
    14 x 48 Drifter with 1100SS Merc

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