View Poll Results: What would you do with a low mileage short block?
Check the bearings and then reassemble and retorque if OK.
16
55.17%
Replace the bearings irregardless of condition.
5
17.24%
Put the oil pan back on and forget about it.
8
27.59%
Voters: 29. You may not vote on this poll
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Cargo Master
Joined: Jun 2001
Posts: 2,571
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From: Oxford, Indiana
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I'm in the process if screwing the motor together for my project truck. The engine only had 10,000 miles on it. I tore it down to the short block for a cam and head swap. So far, everything internally looks great.. Still very clean and the cylinder walls look like they were just honed yesterday. The plan for the new configuration includes a Kenne Bell supercharger, so I want to make sure that the bottom end is tip top before I start putting it back together. I had just planned on pulling a couple rod and main bearing caps to check the bearings and then bolt it all back together and torque it to specs if they were still in like new condition. I was explaining this to my buddy and he was absolutely horrified. He claims that after the caps are torqued and the engine has ran, the bearings have worn in and that removing the caps and then retorquing them will leave them in a slightly different position since there is no possible way to retorque them to the exact original spec and they will wear out in no time. He claims that if the cap comes off, the bearings have to be replaced. I say he is full of crap. I've done this before and never got burnt. I've decided to let you guys make the decision.
Elder User
Joined: Jan 2002
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He's full of it, I've done it many times, and have
yet to have a failure...
Forgot to mention...
I did this on my fathers 3.0L in his old Taurus, when
I was replacing the pan gasket, it ran for another
150K miles... I also did it on an old 289 of mine, it's
still running...
yet to have a failure...
Forgot to mention...
I did this on my fathers 3.0L in his old Taurus, when
I was replacing the pan gasket, it ran for another
150K miles... I also did it on an old 289 of mine, it's
still running...
Last edited by canzus; Apr 4, 2003 at 07:25 PM.
Senior User
Joined: Mar 2002
Posts: 450
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From: Charter Oak, Iowa
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I suppose there could be a little cap shift but I don't think I would be too concerned. In theory, bearings aren't supposed to create a "wear pattern" or take a "set." In practice, tho, they do wear due to the momentary metal to metal contact on startup. Replacing the bearings, I think, would be more critical on an engine that has seen alot of starting cycles. Your engine is relatively new so I don't think I'd worry about it if you do pull the caps. My opinion tho, is unless you are suspicious about problems with the bearings, I'd leave 'em alone and not even check. With 10K on the clock and if no noticeable problems then you've already gotten a "proven" bottom end.
Randy
Randy
Last edited by PigFarmer; Apr 4, 2003 at 08:28 PM.
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Joined: Aug 2002
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From: CA
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Bearings take a set when the cap is torqued. But as long as your using the same bearings in the same places, and you torque them back to the same torque, they should take the same set. Each bearing shell has a tick in it to align it in the cap. It's not likely that they can move enough to ruin the set.
Hwever, even though they can seem to last forever, they do wear, and you say your going to install a blower! If it was me, I'd take the opportunity to install better rod and main bolts (Arp is my preference), new bearings, seals, and a better oil pump (maybe even a windage tray). Except for the bolts, it's cheap insurance!
Hwever, even though they can seem to last forever, they do wear, and you say your going to install a blower! If it was me, I'd take the opportunity to install better rod and main bolts (Arp is my preference), new bearings, seals, and a better oil pump (maybe even a windage tray). Except for the bolts, it's cheap insurance!
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Joined: Mar 2002
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From: Charter Oak, Iowa
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Polkat has a point here. The "crush" of the bearing provides an interference fit that holds the bearing in the rod and cap. Every rod or cap is irregular and unique even after being freshly reconditioned. The crush allows the bearing to custom fit into it's respective rod/cap and lock in. There obviously is distortion to the bearing here but if that was an issue then we'd have to put new bearings in even after a plasti-gage check on a fresh rod. I suppose if the crush height totally disappeared, which it doesn't, after a single installation then new bearings would have to be installed. Pulling the caps and checking shouldn't really hurt a thing as long as the bearings aren't taken out and mixed with different cap/rod partners.
Randy
Randy
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Cargo Master
Joined: Jun 2001
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From: Oxford, Indiana
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Pigfarmer, those were my thoughts exactly. I tried to explain that line of thought to him, but he still disagrees. I'm actually surprised at the poll results thusfar. I didn't think that there would be that strong a showing for just putting the pan back on and forgetting about it. I appreciate everyone's good, well-reasoned comments. I don't disagree with anything that was brought to the table. I just wanted to get my engine stripped down to the shortblock for now (mostly because the old heads, intake, and cam are sold!). I'll be deciding what to do with the rest of it in the next few weeks as my attention turns to putting it back together.
Logistics Pro
Joined: Jan 2002
Posts: 4,907
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From: suburban atlanta
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You don't mention the vintage & engine fambly. The newer rod bolts are torque to yield.... Use once and throw away. If you're going to use any kind of pressure, I'd go with the new bolts & new 'spensive bearings. AND check the clearance. Remember, this engine was most likely assembled with whatever parts came next off the shelf... and you have the time to get those .0001 or .0002 refined fitting bearings while it is upside down and not dripping oil in your face.
If you were not going to be loading the bottom end more than normal, I'd vote for a new gasket and a bunch of pan bolts. Period.
tom
If you were not going to be loading the bottom end more than normal, I'd vote for a new gasket and a bunch of pan bolts. Period.
tom
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just another Rockwell looser
Joined: Feb 2003
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From: Cocoa, FL
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If you are going to pull apart the bottom end you might as well repalace the bearings. They are cheap. and If you want it a solid bottom end you can run a setup from Canton racing that sells a stud girdle and windage tray combo, that uses the correct arp bolts. but i don't know how ' full bore' are you going with this motor.
Steven
Steven
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From: jamesville
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i dont know bout you guys but i NEVER re-tourqe the bearings..Once they are removed..they are replaced. I build hi po engines so i am more picky than most people and i see alot when people bring in blown engines and stuff. if you look closely the bearing will have two raised indentions around it...when you retourqe it the indention becomes wider...unless you line it up PERFECT, something i have never done..when it get wider the oil has a chance to escapse to the outside of the bearing. Instead of traveling the full distance through it. On a HI PO engine, changing them would be mandatory. but for street or mild performance engine. there isnt really a point.. but hey they arent THAT expensive and if you change them then you KNOW what youve got down there...anyways thast my perspective... later
james
james
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Joined: Dec 2002
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From: Monterey bay area
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remove one journal or cap at a time....and inspect...then reinstall with plenty of oil and retorque.....just make sure to prime the engine before startup....
this way you don't run it while dry...
on the other hand.....bearings are cheap......so go get a new set of Clevite 77 bearings....and slap em in.....for peace of mind...
if the engine had good oil pressure to begin with I say slap the supercharger on and go!!!
this way you don't run it while dry...
on the other hand.....bearings are cheap......so go get a new set of Clevite 77 bearings....and slap em in.....for peace of mind...
if the engine had good oil pressure to begin with I say slap the supercharger on and go!!!
Cargo Master
Joined: Aug 2000
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From: SW Michigan
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I wonder if maybe your friend is a bearing salesman ? Or owns stock in Clevite ? I think I would pull the caps off and look at things, but it can go back together with the bearings it has, high performance or not. I've seen a lot of bearings replaced needlessly, just because people thought they were supposed too.....it doesn't hurt to put new ones in, only your wallet. My 390 has used bearings in it, 35 yr old bearings, and I punish it without mercy and it is doing fine. DF
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Cargo Master
Joined: Jun 2001
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From: Oxford, Indiana
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Haven't checked this post in awhile! I never did mention what engine this is. It's a 1984 351W. I built it for my Bronco several years ago, but mother nature dropped a tree on the truck before I got more than 10K on the clock. The engine was plenty strong and had great oil pressure. The only reason that I even opened it up is because it's going from a 4x4 to a street rod. It needs to be recammed and I wanted to swap on aftermarket heads and EFI, too. The blower idea came from a desire to maintain driveability and good street manners and still have serious power on tap without major mods to the EFI system. The bottom end of the engine doesn't NEED to be touched at all. I just wanted the piece of mind I'd get from having a look at the bearings while I'm there. It's either that or leave it alone and put the pan back on. I think it's kinda silly to replace all the bearings on such a solid, low mileage short block "just because they're cheap". Other than pull the heads, pan, and valve train, I haven't done anything to it yet. It's still sitting there waiting for me. The chassis is taking longer to finish than I'd planned.
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Joined: Jan 2003
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From: Balfour
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think of this,if you slap the pan back on and forget bout it, you'll be able get right to tromping on it no breaking in worries
10 000miles is 5% of 200 000miles,plus if you stick in new bearings they can fail too.
10 000miles is 5% of 200 000miles,plus if you stick in new bearings they can fail too.
Logistics Pro
Joined: Jan 2002
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If you built it up several years ago and now intend to put a blower on... if true with the blower, then logic suggests you will want to kick it in the *** fairly frequently, maybe even get other goodies and pump up the boost higher and spin it even faster.
If this is probable, there is a good case to be made for the total bottom end tear down, clearences checked, journals looked at (with a mag glass), faults fixed (crank turned, rods reconditioned)and put bact together with new fasteners, all torqued correctly. Not too time consuming, relativly inexpensive, and very good insurance.
On the other hand, if you are just going to rebuild a normaly driven motor, it is totally OK to just pull the caps and have a look see.
If this is probable, there is a good case to be made for the total bottom end tear down, clearences checked, journals looked at (with a mag glass), faults fixed (crank turned, rods reconditioned)and put bact together with new fasteners, all torqued correctly. Not too time consuming, relativly inexpensive, and very good insurance.
On the other hand, if you are just going to rebuild a normaly driven motor, it is totally OK to just pull the caps and have a look see.