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Cracked block at head bolt hole in my 470

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  • Cracked block at head bolt hole in my 470

    I was torquing the head bolts and the block cracked around one of the bolt holes. What are my options?
    How do I determine what other motor will fit into the boat, because if I'm buying a new motor, maybe I won't go with a 470. It's an 1986 Regal Empress 200 XL.
    Can anyone ballpark the cost of buying a bare 470 block and rebuilding that with the parts I have off the cracked block?
    Thanks in advance for your thoughts.

  • #2
    Re: Cracked block at head bolt hole in my 470

    A picture would be helpful...not all cracks out of a bolt hole in the deck are terminal.
    Cant help with 470 cost, sorry

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    • #3
      Re: Cracked block at head bolt hole in my 470

      Originally posted by Mikeymagoo View Post
      How do I determine what other motor will fit into the boat, because if I'm buying a new motor, maybe I won't go with a 470. It's an 1986 Regal Empress 200 XL.
      Can anyone ballpark the cost of buying a bare 470 block and rebuilding that with the parts I have off the cracked block?
      Thanks in advance for your thoughts.
      There is no other "bolt in" engine. The easiest solution is to stick with the 470.

      e-bay, type in "mercruiser 470 block" or craigs list. Good luck.
      Terry
      87, 4WINNS H 190
      470/Alpha I

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      • #4
        Re: Cracked block at head bolt hole in my 470

        Ayuh,... The 4.3l is the Easiest swap, but it ain't all that easy....

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        • #5
          Re: Cracked block at head bolt hole in my 470

          Originally posted by Bond-o View Post
          Ayuh,... The 4.3l is the Easiest swap, but it ain't all that easy....
          I'll disagree slightly with Bond-o on this one. If you were replacing with a "V" engine (not simple) then you would go with a V8.

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          • #6
            Re: Cracked block at head bolt hole in my 470

            Originally posted by TilliamWe View Post
            I'll disagree slightly with Bond-o on this one. If you were replacing with a "V" engine (not simple) then you would go with a V8.
            I'll disagree slightly with TilliamWe the V6 would use the same gear ratio (1.84) in the outdrive, the V8 should be different ratio (1.5). Additionally the V8 would be about 400 pounds heavier, while the V6 would be about 200 pounds heavier than the 470.
            Terry
            87, 4WINNS H 190
            470/Alpha I

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            • #7
              Re: Cracked block at head bolt hole in my 470

              the V6 would use the same gear ratio (1.84) in the outdrive,
              Ayuh,.... That's my reasonin'....

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              • #8
                Re: Cracked block at head bolt hole in my 470

                Originally posted by stonyloam View Post
                I'll disagree slightly with TilliamWe the V6 would use the same gear ratio (1.84) in the outdrive, the V8 should be different ratio (1.5). Additionally the V8 would be about 400 pounds heavier, while the V6 would be about 200 pounds heavier than the 470.
                You can make due with the 1.84 ratio, if you can get a high enough pitch prop. And the 200 additional pounds of the V6 would wipe out any "gain" in its horsepower rating. I know the 470 is an aluminum block, but I doubt it weighs 400 pounds less than a SBC V8. Can you show me a link to the published weight of a 470 with an Alpha versus the 4.3 or V8 with an Alpha.

                My dad swapped a 5.7 into a boat that had a 470, and was able to use the ratio. And the extra weight didn't affect the ride or handling of the boat.

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                • #9
                  Re: Cracked block at head bolt hole in my 470

                  I'll try to get a picture posted soon. Thanks for the feedback guys. I was wondering if I'm gonna need to replace bearings and have the "new" block cylinders honed or if I can literally take everything off and out of the old block and put it in and on the "new" block. I'm sure it depends block to block, but what is typical. There may be a couple 470 in my area for sale. If buying a running motor is in the same ballpark as a new block rebuild, I might go that way.

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                  • #10
                    Re: Cracked block at head bolt hole in my 470

                    i am in the process of rebuilding a 470, It is a really interesting motor, lots of topics about it. I too was thinking of swap options. As i read more and more i was really bummed about the design issues, that are sure to effect the engine, especially the cam seal issue. As i got mine apart i found on cylinder head was badly pitted due to water in the block. In my case the out drive water pump was not working and the engine overheated, i believe making the head gasket leak. The head on mine was so badly rusted i had to cut off one of the bolts. I felt like giving up on the engine several times, i am replacing all stringers, transom and deck From what i have learned swapping to a 4.3 v6 is the best swap, you will have to redesign and glass in new motor mounts. the 470 usually uses a single large block to bolt in where the 4.3 will need 2 mounts on the side of the engine bay. to get the mounts right you would need to bolt up the rear of the engine align the out drive and then measure the engine mounts, then take the engine out and glass in the new mounts. You also may have to modify the dog house. Shifter/throttle cables may also require some mods. As i read more, there are some good things about the 470 but it takes special care. the aluminum block is quite advanced for its time, and it is a huge 4 cylinder, that is lightweight and gets decent gas mileage. I have decided to stick with the 470, add the alternator kit and repair my cam seal issue, mine did not leak past the second seal but did cut a grove in the cam on the first seal. This is the first engine i have ever worked on, and i had to buy a lot of tools to do it. feel free to PM me if you want to talk directly, i am learning to like the engine despite all the know issues. Of course i may regret that decision. I found a new block and head from a working engine that was burning oil, i am going to try to combine the two, get new rings and hone the new block. I will do a full inspection of the crank shaft as well. gasket kits are not to cheep, they run around 200 i think. There seam to be a lot of blocks available out there but the key is to find one local from someone that knows a little bit about the history of the block, like was it running at all before it was removed and stored. my best advice is to take some time and review as many posts as you can about the engine. i have lots of pictures of the work i have done.

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                    • #11
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                      Re: Cracked block at head bolt hole in my 470

                      So I took a picture but it was too big to post...maybe later ... Had some locals look at the block and they say it's terminal. So I decided to stay with the 470 and I started pricing blocks and motors, and found a motor for $400 with a leaky water pump. Blocks were around $400 unless they needed bored or had other issues.
                      It still has the stator and 3" heat exchanger, but I put the 4" exchanger from the broken block motor and was able to heat up the speedi sleeves, take them off the broken block cam, and put them on the leaky water pump camshaft. I'm going to stay with the stator until it quits and then rewire the alternator set up in. We ran the motor on the floor and it sounds good. We are putting it in the boat tomorrow.
                      Speaking of speedi sleeves, the camshaft measured .871 with the tools we had. This is right in a gap in the speedi sleeve catalog. They have .866 (the range is .861-.866) and then .875 (range .873-.877) so the 470 cam doesn't fall in either range. I find this to be fitting for the 470...
                      Just out of curiousity, which is the BEST way to go? Heat the .866 or locktite/epoxy the .875? The forums say to measure the cam in 3 spots and take they average, but I didn't see anything about the sleeve size gap. I called 2 different places and both quoted the same sizes. I'd like to clear it up.
                      The Mercruiser plate has 5451216 on it, but it didn't come up on the marine shop computer, can someone tell me what year and size the motor is? I know it's a 470, but as Don S. says that's is nothing more than slang ID for a bunch of slightly different motors. The rocker cover has a 488 decal on it, but it isn't definitive.
                      Thanks for you help/advice, just thought I'd share where I'm at with my journey to get onto the water and see if my family and I even like boating...

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