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Unread 01-22-2013, 09:00 AM   #16
82JeepCJ7
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Only other thing I can think of, is somehow -.010 bearings got mixed up with -.020 bearings.

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Unread 01-22-2013, 09:16 AM   #17
Greekcj5
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The bearings were actually stamped with the size. What if the bearings are too tight on the crank?
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Unread 01-22-2013, 09:19 AM   #18
Matt1981CJ7
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Originally Posted by 82JeepCJ7 View Post
Only other thing I can think of, is somehow -.010 bearings got mixed up with -.020 bearings.
His crank was turned to .020" under.

Matt
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Unread 01-22-2013, 09:20 AM   #19
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Originally Posted by Greekcj5 View Post
The bearings were actually stamped with the size. What if the bearings are too tight on the crank?
Then you need thinner bearings, or have the crank re-turned.

Gotta run. Good luck.

Matt
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Unread 01-22-2013, 09:21 AM   #20
Greekcj5
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Originally Posted by 82JeepCJ7 View Post
Only other thing I can think of, is somehow -.010 bearings got mixed up with -.020 bearings.
Wouldn't .010 bearings give me more clearance though seeing as they're undersized?
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Unread 01-22-2013, 09:27 AM   #21
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Then you need thinner bearings, or have the crank re-turned.

Gotta run. Good luck.

Matt
So basically because the bearings came from the machine shop and he didn't have the pistons to fit on it its possible he got bearings that are too thick.
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Unread 01-22-2013, 09:40 AM   #22
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So basically because the bearings came from the machine shop and he didn't have the pistons to fit on it its possible he got bearings that are too thick.
What? The pistons don't have anything to do with the bearings. Neither do the connecting rods if that's what you really meant.

If your crank was turned 0.010 undersized you need 0.010 undersized bearings. They should be marked as to what size they are and your machinist should have told you what the crank was turned to. It's simple to verify.
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Unread 01-22-2013, 09:59 AM   #23
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I understand that. The problem is i just found out he had another shop turn the crank but my machinist bought the bearings. According to the guy who turned it he turned it to .020 under and that's what the bearings are stamped at. Can i verify it by mic-ing the crank journals and then the rod end with the bearings on after torquing the rod end cap? Bear with me..I want to learn and do it right. Thanks
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Unread 01-22-2013, 10:38 AM   #24
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According to the guy who turned it he turned it to .020 under and that's what the bearings are stamped at. Can i verify it by mic-ing the crank journals and then the rod end with the bearings on after torquing the rod end cap? Bear with me..I want to learn and do it right. Thanks
Perhaps reading this thread will help you...
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Unread 01-22-2013, 10:39 AM   #25
swatson454
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You might want to start from scratch. Lay the crank in place and plasti-gage the thrust bearing. If all looks good, clean up the journal and torque that cap down and check rotation. If it spins freely with the thrust cap torqued down, repeat the process for each main cap, checking rotation every time.

If you make it that far with no rotation issues, start installing piston/rods. Make certain that the expander ring is butted together and NOT overlapping. Make sure that the piston slides right into the bore with no fuss. If you have to finagle it, it's possible to roll a thin oil ring right over and that's no good. Plasti-gage the rod bearing. If that goes well, clean up and oil the journal and torque the rod cap. Check rotation. Repeat.

If you check rotation after each step, you'll know right where your problem is.

It's also quite common for bearings to be all over the place as far as actual clearance goes. You may have to plasti-gage all of the journals and see if you need to shuffle the shells around a little.

Also, spray a paper towel with a shot of WD-40 and wipe each cylinder. If the towel comes out with anything on it, that bore needs to be cleaned a little better.

Hope that helps!


Shawn
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Unread 01-22-2013, 10:48 AM   #26
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Thanks Swatson. so far i torques the main bearings and did it like u said. It spinned freely after they were all torqued down. The rings are good and well seated so i guess the only step i nerd to do now its plastigauge one by one torquing as i go right?
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Unread 01-22-2013, 10:55 AM   #27
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That's how I'd skin that particular cat

Try to get a really accurate reading on the plasti-gage (oxymoron) for each journal; you may need to shuffle the bearing shells around to make each rod happy.


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Unread 01-22-2013, 10:57 AM   #28
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Perhaps reading this thread will help you...
Thanks
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Unread 01-22-2013, 10:59 AM   #29
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See i had no clue bearings could be machined differently. I figured they're done with precision so they'd all be exactly the same. Thanks
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Unread 01-22-2013, 11:22 AM   #30
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What I like to do is install the bearing caps with the bearings installed, but no crankshaft. Mic the ID of each and write it down in sequence. Then Mic each journal in the same sequence. Do the math and determine the clearance at each position. At that point you can see which bearings might be tighter or looser than others and move them based on the math to get each clearance at each journal as close to spec as possible. Seeing you mention helicopter mechanic work makes me think you probably have access to micrometers and snap gages.
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amc 304 , cj5 , crankshaft , engine rebuild

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