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671TI 485HP

Discussion in 'Engines' started by RossC, Jun 6, 2023.

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  1. RossC

    RossC Member

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    These engines have 2200 hours in a 84 Viking aft cabin. Original, never rebuilt. General consensus seems to be that the 671 pushed to 485HP is a ticking time bomb. If they were in a sport fisher I would think they were probably run hard. In a aft cabin MY, maybe not. Am I asking for trouble here? I'm hoping the broker will let me do a cold start.

    Other than a cold start, watch for smoke and how long it takes to clear, is there anything else I can do without getting a DD mechanic involved?
  2. Capt Ralph

    Capt Ralph Senior Member

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    I had a customer with a Californian and Covington 6-71TIBs. Boat was falling in on itself,, but ran great, made HP, sucked fuel.
    I actually like that engine.
    Keep your hands off the throttles and it would run well slow.
    The only reason the that 71 can reliably push that much abuse was because it was a straight 6 and have crank bearing between every rod throw.
    It is a high performance engine and the ponies need to be set loose from time to time, As any 2 stroke Detroit, to blow out da gunk.

    They offer rather large side port access so your (real DDC survey guy) can inspect the liners rather well.

    BTW, that Californian was a artificial reef candidate last seen, but ran great.
  3. Pascal

    Pascal Senior Member

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    At that HP they are pretty high strung but it all depends on how they ve been run. 2200 hours in almost 40 years is only 50 hours a year. That’s a bit low and they could have some internal corrosion.

    If the rest of the boat is ok, make an offer contingent on sea trial with cold start to verify perfomance BEFORE survey. Then do the engine survey first which will include oil samples, liner examination etc. then if that passes do the hull survey. If the seller balks at splitting the survey then ok but I would not spend a dime on surveys without a pre survey sea trial with cold start
    Capt Ralph likes this.
  4. RossC

    RossC Member

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    That might be difficult. There some growth on the bottom from sitting over the winter. If you were to run it up now without cleaning the bottom, you won't get accurate performance metrics. I'm hoping to do a cold start today before even talking money.
  5. Pascal

    Pascal Senior Member

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    It s up to the seller to present a boat that’s ready to be sea trialed once you have a contract. He can hire a diver to clean the bottom or do a short haul and pressure wash.

    unless the boat is an exceptional deal, I wouldn’t gamble a few thousands in surveys just to find out the boat can’t get on plane, has a bad vibration or smoke on acceleration

    especially a dock queen ran 50 hours a year
    MBevins and Capt Ralph like this.
  6. RossC

    RossC Member

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    That one is no go. It was used as a floating condo for 7 years. Insane amount of deferred maintenance, interior leaks and hasn't seen a wash and polish in years. The engines are J&T but the valve covers were almost touching the floor so couldn't read the tag. To open the hatches above the engine would require removing the salon carpet. Owner and broker didn't know if they are TI's or TIB's. Broker also said that a previous potential buyer made a deposit and requested a sea trial first then haul and survey. He said when they took the boat out, it ran pretty good but the owner would not allow the surveyor to push it past 1500RPM. Buyer backed out at that point. I would have backed out also.
  7. Capt Ralph

    Capt Ralph Senior Member

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    If they are truly 485 HP, then they are TIBs. No other way to make that much HP
    The B is for by-pass blower.
    At higher RPM, that big asp turbo is pumping lots of boost pressures to the air box, thru the blower. The blower rotors are dis-engagd from the gear train and free spin so not to restrict that hurricane blowing thru them.
    Was J/T cast in the heat exchanger? Covington was the usual Detroit vendor.
    Any pictures??
  8. Pascal

    Pascal Senior Member

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    Running thru the RPM range is a must during survey including a brief time WOT to see what it turns. This a normal reasonable request. The boat will never sell… Run Forrest, Run.

    I ve had one surveyor request something I considered unreasonable… on an 84 footer he wanted me to go from idle to wot almost instantly. I refused and said I d will not go to WOT in less than 15 seconds. Too much stress on the drivetrain. I explained that to the buyer and he concurred.
  9. MBevins

    MBevins Senior Member

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    Your wise to run, if you can't open the hatches due to a carpet you know there's be zero maintenance on the boat. It's a shame because they really are great boats.
  10. RossC

    RossC Member

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    There was a J/T sticker on the side of the valve cover. Couldn't see much else without pulling up carpet to open up the floor. Based on the rest of the boat, it wasn't worth moving forward.
  11. Al Perna

    Al Perna New Member

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    Where was the boat located may i ask ? Sounds like the one I just purchased lol
  12. RossC

    RossC Member

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    Viking aft cabin in Essex, MD.
  13. Al Perna

    Al Perna New Member

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    thank you not the same boat. Mine also sat for a while however I think I have enough boat to bring her back . I also would bet there are more aft cabin boats being used as liveaboards than not. Our goal is to have a condo cable of weekend runs . Then move her with the weather to other locations .
  14. Noname

    Noname New Member

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    Most likely TI.s in that boat in 1984. Seen TIB.s in 1987 44 Aft Cabins. I have TIB.s in my 1988 45 Convertible. The engines need to run, sitting is not good.