Bearing Installation Seat, Wet or Dry?

[11secAvanti]

This question has to do with the installation of mains and rod bearings. When the bearings are seated in their slots should they be installed dry or with a smidit of oil? I smear a few drops on the back side of the bearing before I seat them if I plan to store the short block for an unknown period of time. If I plan to fire it very soon I put them in dry. I read it should always be dry to insure heat transfer away from the bearing to the main web. Is this a big deal. I recently installed and fired a back up short block that I assmbled over 5 years ago. I oiled the back side to deal with time and condensation/humidity issues. I do the man and rod cap ends the same way. Again, is this a big or insignificant deal?

[Trev]

I will reply seeing no one replied.

I am no expert but i do have a few big enggines under my belt and i would never, not ever, put oil on the backs of any shells.
It will stay ther and affect your clearance.

Trev

[k-star]

I personally clean the back of my bearings with wax and grease remover last thing before i install them.....So they are dry and free from oil and dirt.

I have never used oil on them. I have been told about the oil changing the bearing size but i personally have never did the research to see if it's true. Or the amount it would change the size.

I really cannot see why you would want oil on the back side????

Keith

[learner]

I don't recommend oiling the back side either. If your looking for rust preventative, i would use WD-40.

[crazycuda]

I have found that using oil on the back side of a bearing will change the clearances.
using 5w30 decreased clearances .001
using 20w50 decreased clearances .0015

These are not dead set numbers becaused I used plasti ga to check and since plasti ga is just an approximate measurement, not an accurate micrometer measurement

[OldSStroker]

Anything between the bearing shell and the block/cap can act like an insulator and slow down heat transfer to the block where the heat can be rejected into the coolant or oil. This could lead to local overheating at the bearing. Clean and dry is probably the best contact, IMO.

[ChrisU]

agreed about the clearances. I found it while checking clearances once. Don't remember the numbers as it's been a long time. Something to consider when checking for clearances.