When to bore .030

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Markstrimaran
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When to bore .030

Postby Markstrimaran » Thu Sep 28, 2017 6:39 pm

6.2 Detroit, with 40k, light rust on cylinder walls.

The last photo was with head just pulled. It cleaned up very well with steel wool. No scoring, cross hatches still noticeable.
Should have taken one last after photo.ImageImageImageImageImageImage

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Tatsadasayago
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Re: When to bore .030

Postby Tatsadasayago » Thu Sep 28, 2017 7:03 pm

Isn't the 6.2 sleeved? It looks like that one spent some time underwater.
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Markstrimaran
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Re: When to bore .030

Postby Markstrimaran » Fri Sep 29, 2017 3:56 pm

I don't think they are sleeved. Cummins are.

Well I would like to bore .010 and intall new pistons with new rings, but don't have a grand to spend.

So still need to get a engine stand, well build one, to get the crank and piston out.
Before I can tell much more.

Thinking a very slight hone, then go .010 rings on stock pistons.

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Tatsadasayago
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Re: When to bore .030

Postby Tatsadasayago » Fri Sep 29, 2017 4:36 pm

The bore looks like it was in great condition before the water intrusion. +.010" rings with a good bar hone job ought to fix it up nicely. Might want to watch the end gaps though...
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SJTD
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Re: When to bore .030

Postby SJTD » Sun Oct 01, 2017 8:33 am

.01" Rings in a standard bore after a few tenths of honing. Is that often "done" on these?

Seems way to tight even with proper end gap. And the support on lands would be less than normal maybe encouraging them to rock?

After some thought I suppose not. I'm guessing the width of the rings are the same.
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Nikkormat
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Re: When to bore .030

Postby Nikkormat » Tue Oct 03, 2017 11:42 pm

Knock on wood before reading, but my first 401 had worse bore rust than that and it cleaned up with scotch brite and a hone job. Still has stock pistons and rings despite 130 ish k miles before I tore into it. It even had a noticeable ridge at the top of the cylinder. And it still has compression 25k miles later. As I said, knock on wood...


Point being, I think you'll be fine.
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eggman918
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Re: When to bore .030

Postby eggman918 » Fri Oct 06, 2017 9:05 am

I was in a similar situation with my 4BT it would have cleaned up with a professional hone BUT it would have been right at the max limit for piston to wall clearance that Cummins says is acceptable. So between the need for proper compression for a diesel and the expected lifespan of the B series Cummins I chose to bite the bullet and went .020" over..............$.02
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Markstrimaran
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Re: When to bore .030

Postby Markstrimaran » Fri Oct 06, 2017 10:01 am

Been busy working Saturdays, Thanks for the advice.
No shut downs until Christmas. So only dreaming till then.

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Markstrimaran
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Re: When to bore .030

Postby Markstrimaran » Fri Mar 16, 2018 7:36 pm

Markstrimaran wrote:Been busy working Saturdays, Thanks for the advice.
No shut downs until Christmas. So only dreaming till then.

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Have one cylinder in need of boring.Image
The diagonal band is a worn area.
Piston rings were stuck,Image


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Stuka
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Re: When to bore .030

Postby Stuka » Fri Mar 16, 2018 8:07 pm

Looks like 10 over and you would be fine. I don't know much about those engines or how much over bore is too much. But I would personally go the minimum needed.
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Markstrimaran
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Re: When to bore .030

Postby Markstrimaran » Fri Mar 16, 2018 8:33 pm

Markstrimaran wrote:
Markstrimaran wrote:Been busy working Saturdays, Thanks for the advice.
No shut downs until Christmas. So only dreaming till then.

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Have one cylinder in need of boring.Image
The diagonal band is a worn area.
Piston rings were stuck,Image


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Any idea why the one piston had the side ground down?

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Markstrimaran
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Re: When to bore .030

Postby Markstrimaran » Fri Mar 16, 2018 9:00 pm

Stuka wrote:Looks like 10 over and you would be fine. I don't know much about those engines or how much over bore is too much. But I would personally go the minimum needed.
I am going .030 on the one cylinder, and install new std to .010 rings on the rest.

It might work, as Its a 6.2 diesle , @ 2200 rpms, not a 350 @ 5000 rpms, I can buy running 6.2 for the price of pistons and rings. Worst case is in 5 years at 25,000k the motor is seized.

Then I can bolt in a replacement, right now, I need a running power train to swap with. The tranny and transfer case are ready to go, I hope.


I will take the block to a machine shop,
for the bore, unless some one can convince me that 30.00 bucks is robbery. It's $200.00 for all 8, but the price of new pistons and rings.

I have alot of other expenses, to look at. Big wheels, lift, exo skeleton, turbo maybe. Arb lockers, maybe 4:11 Dana 60s.

I am guessing the 3:73 gears are going to match up well with the diesels lower RPMS.


The motor,trany,t case, in the jeep are for SALE, also to help fund the project.

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