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Im taking my 454 engine to the shop tommorow and wondering what tolerances I should run on rod and crank bearings. Also what skirt clearence do i run? My sealed power hypers spec sheet says .0015" but I assume thats for auto use not marine. Do i just stick with the manufactures ring end gap?

thanks!!
 

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Interesting question I asked the same thing and got no reply . I took mine to a engine builder who had built jet boat engines and let him do his thing .
 

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Interesting question I asked the same thing and got no reply . I took mine to a engine builder who had built jet boat engines and let him do his thing .
I think that is the answer to the question. You shouldn't have to tell an engine builder (reputable) how to build an engine.
 

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Welcome to the boards. All this info. and so much more is readily available in the dyno section. Pop on in over there, introduce yourself, and ask away. You can also do a thread search there and retrieve most of your desired answers. Good luck with your project. Post up some pics. of your ride over here too so we can see what your toying with.
 

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Im taking my 454 engine to the shop tommorow and wondering what tolerances I should run on rod and crank bearings. Also what skirt clearence do i run? My sealed power hypers spec sheet says .0015" but I assume thats for auto use not marine. Do i just stick with the manufactures ring end gap?

thanks!!
At this point you have my answers via the PM's we have been sending, but once again, will stick to my answer about piston to wall clearance with the hypereutectic pistons, since I would not advise their use in a high performance marine engine. You should try calling Sealed Power to see if they have a tech line.
 

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I totally agree except in my area bbc jet boats are not common.
If this is the case you better search around a bit. You may regret giving your money to a guy with no jet motor build experience, even if you take it back, it may blow up again because the same guy is doing it. Good luck getting your money back, and pretty soon you will be hearing things like, you got out of the water and over reved it. I know a guy that went through this and only after paying the guy on the 3rd motor pull he is selling his SWTD with a motor that is gonna be good for a mile or two. GOOD LUCK
 

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Im taking my 454 engine to the shop tommorow and wondering what tolerances I should run on rod and crank bearings. Also what skirt clearence do i run? My sealed power hypers spec sheet says .0015" but I assume thats for auto use not marine. Do i just stick with the manufactures ring end gap?

thanks!!
X.s 2 on the hyperutectics ,Barry has given you good advice , for the very little $ you might save you will likley regret it later. Go with a decent Forged Piston. Re the rest of your build , If you belive your machine shop lacks the knowledge or capability to build this motor , might be time to do some research and shop around
 

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At this point you have my answers via the PM's we have been sending, but once again, will stick to my answer about piston to wall clearance with the hypereutectic pistons, since I would not advise their use in a high performance marine engine. You should try calling Sealed Power to see if they have a tech line.
X2 He knows what he's talking about that's for sure
 

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X.s 2 on the hyperutectics ,Barry has given you good advice , for the very little $ you might save you will likley regret it later. Go with a decent Forged Piston. Re the rest of your build , If you belive your machine shop lacks the knowledge or capability to build this motor , might be time to do some research and shop around
X2 He knows what he's talking about that's for sure
I won't go so far as to say they won't work, lots of engines running around in boats with cast pistons, but in the overall cost of the project it's probably not worth the risk.
 

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Quote Originally Posted by jetboatperformance View Post

X.s 2 on the hyperutectics ,Barry has given you good advice , for the very little $ you might save you will likley regret it later. Go with a decent Forged Piston. Re the rest of your build , If you belive your machine shop lacks the knowledge or capability to build this motor , might be time to do some research and shop around





Quote Originally Posted by BigSteve View Post

X2 He knows what he's talking about that's for sure
I won't go so far as to say they won't work, lots of engines running around in boats with cast pistons, but in the overall cost of the project it's probably not worth the risk.

OP,
Check out the KB Icon forged pistons, they are very nice.
 

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Pistons? Strongly suggest you use forged. Are you going to run a thermostat? Once you have an idea of that, contact the piston manufacturer for thier clearance recommendations. They will have guides for street and marine among others.


Rod and main clearances, the Mercruiser Manual for 454 with standard crank is .0025 to .003 on the rods with side clearance of .020 to .026. Mains are .0025 to .003.


My last engine (540BBC) with standard crank ended up being .0022 to .0023 on the rods and .0032 to .0029 on the mains. Have five seasons of skiing, tubing with a few races thrown in with no problems.

Good luck. Hope I have not added to the confusion.
 
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