Bearing diagnosis

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77cruiser
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Bearing diagnosis

Post by 77cruiser »

Tore down my 385 sb with about 18K miles. Engine had good oil pressure 20-25 idle 50 at 2000rpm, 15-40 rotella.
Rods all looked about the same they had .002 pastiguage Mains were .003 .0025 .0025 .0025 .002 .003 F---R.
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Re: Bearing diagnosis

Post by CharlieB53 »

How sure are you as to the straightness of the crank?

The one bearing shell not showing much wear at all and progressively worse wear along the row of bearings makes me want to get the dial indicators out and check that crank very closely to prevent this happening again.
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Re: Bearing diagnosis

Post by engineguyBill »

Could be a combination of hour-glass shaped journals and contamenents/debris in the oil.

Lower viscosity oil would probably better choice with .002" rod bearing clearance and "reasonable" clearances on the mains.
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modok
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Re: Bearing diagnosis

Post by modok »

Mostly looks OK.

Center mains might have too much crush.
#1 a little twisted, loose in register?
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Re: Bearing diagnosis

Post by 77cruiser »

Not sure on the crank being straight. Wasn't line honed, should have been & the caps don't fit real tight.
Don't have any plans of using the same block again, just don't want another build to look like that after a short time.
Next thing is the timing set that came out of it, should've lasted longer, yes?
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Re: Bearing diagnosis

Post by modok »

Whoa, that's not right.

Far as "looks" tri-metal bearings aren't known for winning beauty pageants.
You want them to look good get some aluminum bearings, but that's just hiding the truth. From what can be seen I'd say those bearings were working just fine considering.
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Re: Bearing diagnosis

Post by MadBill »

Surely the chain was super loose, to climb the teeth like that?
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.
user-23911

Re: Bearing diagnosis

Post by user-23911 »

Wrinkle finish on the crank journals?
With added clearance?
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Re: Bearing diagnosis

Post by Geoff2 »

Teeth on sprocket look like they have snapped off?

Rolon brand t/chain?

I have one here. Has Rolon on one side, other side says India....
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Re: Bearing diagnosis

Post by Geoff2 »

Teeth on sprocket look like they have snapped off?

Rolon brand t/chain?

I have one here. Has Rolon on one side, other side says India....
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Re: Bearing diagnosis

Post by BigBlockMopar »

Street engine?
Engine cr?
20-25 oil pressure at how much idle rpm?
I'm no pro-builder but with a rather 'thick' oil like that I would've liked to see more pressure at idle, at least 30+ psi.
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Re: Bearing diagnosis

Post by mag2555 »

Take a gander here!
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Re: Bearing diagnosis

Post by 77cruiser »

MadBill wrote: Sat Dec 09, 2017 11:52 pm Surely the chain was super loose, to climb the teeth like that?
It had about 1/4 inch play, but it shouldn't have been that loose with the mileage it had.
Comp I think, chain is marked USA.
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Re: Bearing diagnosis

Post by CharlieB53 »

Barring other serious problems with this block I don't see why it cannot be align honed, caps tightened or pinned and re used again.

Timing chain must have been too slack with the gear set used. Look into better parts on your next build. If the chain still seems too slack on assembly then find out why.
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Re: Bearing diagnosis

Post by 77cruiser »

bigblockmopar wrote: Sun Dec 10, 2017 7:12 am Street engine?
Engine cr?
20-25 oil pressure at how much idle rpm?
I'm no pro-builder but with a rather 'thick' oil like that I would've liked to see more pressure at idle, at least 30+ psi.
Yes street engine 9.75 cr.
Idle rpm about 750-800.
That oil press. was with a HV pump.
Timing chain was tight when I 1st put it together.
Jim
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