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977.3Ford 
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Joined: 04 Oct 2019
Location: Dayton, Ohio
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 Topic: 426 bearing questions
Posted: 26 Aug 2025 at 7:43pm |
Had a post the other day about my 8050 throwing a rod, ended up finding a deal locally on an engine out of a late N6 with 4500 hours. I pulled a main and rod cap off last night, they show some wear, nothing too crazy though. Need to get this engine back in ASAP, but i'd like to roll new bearings in while the pan is off. Rod bearings and bolts seem pretty straightforward, the main bearings have me a little confused. From reading around it looks like to use new bearings i would have to drop the crank and plug the holes in the block, but i've seen a couple posts talking about just replacing the bottom shells and leaving the tops in. Given how these bearing looks, is that the way to go?
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Jimmy
1982 8050 Powershift
1982 6080
1992 R52 Gleaner
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DrAllis
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Posted: 26 Aug 2025 at 10:15pm |
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If it was mine, bottom shells is all it would get.
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NEVER green
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Posted: 27 Aug 2025 at 7:54am |
I have gone that route a couple times.
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2-8050 1-7080 6080 D-19 modelE & A 7040 R50
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SteveM C/IL
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Posted: 27 Aug 2025 at 8:12am |
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That main looks really good especially if it's got all those hours. I agree with just replacing lowers. What's the date on the back?
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tbran
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Posted: 27 Aug 2025 at 8:50am |
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Yup, also I would definitely go back with ARP rod bolts thru Agco. It probably doesn't apply here, but there was also a bulletin about reversing the slotted rod brg / rod position - do you remember anything about that Doc ?
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When told "it's not the money,it's the principle", remember, it's always the money..
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DrAllis
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Posted: 27 Aug 2025 at 9:23am |
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Yes. On older engines with 4-rings pistons, you are to turn the conn rod 180 degrees when reassembling. So, any of the 4-ring/small piston pin engines pre-8000 series this applies to.
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HudCo
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Posted: 27 Aug 2025 at 9:42am |
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is thier anything about rod and main bearing changes in the knowlage section might be good to have those service bullitins thier be cause that gets confusing if you are turning rods backwards and plugging oil holes an older manual my not show the correct changes
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tbran
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Posted: 27 Aug 2025 at 10:00am |
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OK so his N6 replacement engine will have the 3 ring piston -big pin- and this will not apply. This will be the rifle drilled rod just like the 8000.
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When told "it's not the money,it's the principle", remember, it's always the money..
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plummerscarin
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Posted: 27 Aug 2025 at 12:12pm |
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What was the purpose of flipping the connecting rods?
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SteveM C/IL
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Posted: 28 Aug 2025 at 7:49am |
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Testing showed better wear with the flip. If you look at brg you see more material to one side VS other. The direction of rotation applies load to more brg material. I could get the direct quote from service manual but....
I strongly suggest using the 2 feeler guages between rod and crank to help keep cap square. Kinda a pain but doable.
Edited by SteveM C/IL - 28 Aug 2025 at 7:52am
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DrAllis
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Posted: 28 Aug 2025 at 8:24am |
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I was always taught to snug the rod bolts. Then take a hammer and tap the end of the rod cap sideways both ways. This will square the cap and then tighten/torque the bolts. I had a kid one time decades ago who didn't do that on a 190XT engine OH. The engine idled about 30 seconds and locked up from the corner of the rod cap gouging into the crank throw side. Careful dressing in-chassis with a die grinder (by me) saved the day. He was soooo close to being fired that day because he had been told the proper procedure and didn't do it. He just didn't think it was that important.
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SteveM C/IL
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Posted: 28 Aug 2025 at 4:23pm |
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That's the way I did the first one. It's still running.
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ACjack
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Posted: 28 Aug 2025 at 8:06pm |
 DrAllis wrote:
I was always taught to snug the rod bolts. Then take a hammer and tap the end of the rod cap sideways both ways. This will square the cap and then tighten/torque the bolts. I had a kid one time decades ago who didn't do that on a 190XT engine OH. The engine idled about 30 seconds and locked up from the corner of the rod cap gouging into the crank throw side. Careful dressing in-chassis with a die grinder (by me) saved the day. He was soooo close to being fired that day because he had been told the proper procedure and didn't do it. He just didn't think it was that important. |
That’s the same procedure that was used at the factory on the assembly line. After the caps were torqued a feeler gage was used to check for proper side clearance.
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DougG
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Posted: 29 Aug 2025 at 4:11pm |
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Hey! Good to see you here ACJack,, tell us some Allis Chalmers stories,,, some that really stick out in your mind,,, some good ones and head scratchers,,
Edited by DougG - 29 Aug 2025 at 4:12pm
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