Rod bearing replacement

[BIGAIR]

Just installed a new cam, no machine work to block, just replacing the cam, lifters, springs, etc. While I have the engine out, I thought I would replace the rod bearings. My friend said not to do that because of the tolerences involved and I did not do a complete engine rebuild and have the crank turned. I pulled #6 bearing and saw just a few scratches exposing copper, seemed like normal wear. So should I just bolt it back up or can I get away w/ putting in the bearings w/o machining the crank?

Thanks

 

[WarWagon]

If none of your bearings have spun to this point I'd say put a new set in it or put a set of .001 undersized rod bearings in instead if you want the clearances a little tighter without machining the crank.

 

[thadeal4real]

when it comes to bearings you always need to check clearances

 

[BIGAIR]

Thanks guys,

No problems w/ the current bearings, just thought I would replace them since the engine was out. I understand that bearing clearances should be checked, but is it so critical if replacing with the same manufacturers part # and size?
Should I just leave the current ones in there?
FYI-What lead to replacing the cam was a blown head gasget so water and debris was obviously everywhere and on everything, so another reason to replace the bearings IMO

 

[turbodave231]

You can replace the rod bearings if you don't have any scoring on the journals and clean the rod journal carefully (don't get anything in the oil hole). Plastigage the new bearings to see where the oil clearance is at.

Plastigage isn't a substitute for measuring, but it will tell you if you're in the ballpark.

Like the previous post said, you can use .001 undersize bearings if the plastigage shows too much clearance. Torque the rod bolts to 45 lbs/ft with clean oil on the bolt threads.

Dave

 

[forzfed]

What everyone above said. I'd also break the bearings in, go easy for the first 500 clicks.

 

[BIGAIR]

Thanks guys,

Will do. Called Duttweiler and was told the same thing. It'll be back together this weekend. Hopefully fired up/runnin' next weekend. (trans is out gettin' Lonnie's new t-brake) Keep you posted.

Thanks again, appreciated.