Extra Clearance Bearings, Use One half, Top or Bottom?

[n2omike]

With extra clearance bearings, I know you can use only one if only half a thou is needed. I believe I remember it being said it's best to use the extra clearance bearing in either the top or bottom... but cannot remember which.

So, do I put the looser bearing shell in the top or bottom... or does it really matter?

Thanks!

[engineguyBill]

Bearing manufacturers recommend installing the thicker bearing shell in the lower position for main bearings and the upper position for rod bearings. However, I and many others have installed the thicker shells in the upper position main bearing location and the lower position of the connecting rod with no problems.
In summary, I recommend going by the bearing manufacturer's recommendations . . . . . . .

[n2omike]

Bearing manufacturers recommend installing the thicker bearing shell in the lower position for main bearings and the upper position for rod bearings. However, I and many others have installed the thicker shells in the upper position main bearing location and the lower position of the connecting rod with no problems.
In summary, I recommend going by the bearing manufacturer's recommendations . . . . . . .

Thanks for the reply, Bill. I appreciate it!

[BlitzA64]

I have used them both ways myself, never saw an issue either way on disassembly. I guess like Bill said go with the bearing mfg suggestion, I always saved the extra bearings to use rather than use half a set then throw away the rest

[needforspeed66gt]

I have used them both ways myself, never saw an issue either way on disassembly. I guess like Bill said go with the bearing mfg suggestion, I always saved the extra bearings to use rather than use half a set then throw away the rest

Yep - I've done this too many times to count, never a problem and they look exactly the same on teardown.

[modok]

I was taught to use the thinner shell in the cap.

I can imagine some situations where the reverse would work better, tho it would be a rare case.

[BILL-C]

We have used the thinner halves in either location in several hundred race engines with no issues.

[PFC1]

Maybe the bearing companies recommend only using certain halves in certain locations so you'll waste more bearing/thus they sell more. Just a thought. I regularly use them both ways w/o issue.

[EDC]

Would it really make a difference?

As long as the "thick" shells were installed on one side and the "thin" on the opposite, how would the crank/block know?

We're talking a .0005" delta?