Bearings And Clearances

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i have a friend with an rb25det in a 180 and we noticed some blow by so we did a compression test and sure enough the number 5 cl was indicating 130 psi.

what i need to know is, can we take down the motor and take out the number five piston and replace it with another, using the same conrod and bearing is that safe, or should he buy acl race series bearings and replace the whole bunch, i read somewhere here that you torque down the big end to 40 pounds.

ive also read that the factory rod bolts stretch and give the wrong readings, do i need to purchase arp rod bolts.

why im asking is no one builds motors here in the bahamas and we'd hate to ship it over to the united states for an issue with one piston, shipping alone is $1200.00 US.

please help havent got a clue

[r33_racer]

if its just poor compression, that normally indicates that the rings have lost tension. If the pistons are fine, as in no signs of det on the crown or ringlands. All you really need is a new set of rings, gap them for each cylinder and do them abit tighter then normal. That would be a cheap and easy way to help solve the problem. If the bearings look fine, there is no need to change them. Most people just over torque the bolts a little extra to overcome the stretch....5-10% extra roughly. I did that in my car and ive had no issues....std rods and bolts.

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thanks thats good news

so you only change bearings when the motor knocks