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Old 01-31-2017, 10:28 AM   #1
Scooby Newbie
Member#: 241316
Join Date: Mar 2010
Default Rod bearing clearances.. to oversize or to not oversize

Rebuilding my ej257 after it spun rod bearings on the dyno. I keep going back and forth and can't decide what to do. The clearances with new std bearings on the rods is .0015-.0017. I'm considering going with .001 over size to loosen them a bit. I'm trying to make sure I don't lose another engine on the dyno.
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Old 01-31-2017, 11:39 AM   #2
Scooby Specialist
Member#: 30804
Join Date: Dec 2002
Chapter/Region: SWIC
87 Yugo


If you are seeing .0015-.0017 with std bearings then the X will ideally give you .0025-.0027. In reality it will most likely come out to .0022-.0025 from what I have seen. In my opinion this is too large for the standard wet sump setup.

I personally would be happy with the .0015-.0017, BUT main sizing does become a factor here. I also try and get rods 2 and 3 to match as closely as possible on the clearances since they share oil supply.
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Old 01-31-2017, 11:41 AM   #3
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Member#: 383633
Join Date: Mar 2014
Chapter/Region: RMIC
Location: Yampa, CO
2002 Impreza WRX


I would be fine with those clearances. Do not oversize them.
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