My boat has a knock, I don't know how it happened.

[baconbiscut]

Re: My boat has a knock, I don't know how it happened.

come Monday, we're ordering a 383 long block from from US engines, I will fill everybody in as things progress, hopefully, I can get my camera back from my buddy, so I can film the maiden voyage of the new engine.

-Dan

 

[baconbiscut]

Re: My boat has a knock, I don't know how it happened.

Had the new engine put in yesterday from US engines. I'm go pick up the boat after school today I'll post a vid so everyone can see the end result.

-Dan

 

[z284u2try]

Re: My boat has a knock, I don't know how it happened.

Wait a second... You are saying that you have a 6.2 mpi motor that scored the crank and may need some bearings? And you want to replace the whole short block?



At best you can disassemble the motor and have the crank cut .010 under on both the rods and mains install new bearings and an oil pump. Don't forget to clean the block until you are sure there is no debris in the motor.

By the way a rebuilt short block will most definately have a .010 under crank in it anyway.

The other way is to buy a balanced rotating assembly and install it in the block you have. The bores would need to be deglazed (honed) and everything cleaned up real good. (Same thing for a bearing change) and put the motor together.

Minimal machine work and a rotating kit in the 5 to 700.00 dollar range and you would be good to go.

If it were mine I would disassemble the motor and have a look. Cutting the crank and installing new bearings is not that hard to do and you could probably have the motor back together for less than 350.00 Plus you would know what you have.

That rebuilt motor may have a .020 or .030 under crank.

Ps Detonation in the form of a ping can take out a set of rod bearings in short order. But that can be determined upon teardown. It would benifit you to see why the motor has a knock not just that it has one.

This is what needed to be done.

In my opinion a piece of trash damaged that crank. Ever started a new engine run it and drain and strain the oil? Did you change the oil after its first start up? The only way I see that crank getting scars in it that you can run a finger nail in is something got in there. I would have checked the bearing clearance against what the manufacturer says it is. If you have the wrong valves in it whats to say it had the wrong bearings or main cap bolt tq? Any pics of the crank?

Are we talking rod bearings here or crank mains?

tulliped two intake valves
I have seen this happen once in my life from way lean condtion.