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Selecting bearings for RB25DET NEO

DTT_Eruc
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SteveL Mentor

SteveL

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Posted
6 hours ago, DTT_Eruc said:

What's the oem specs for clearances on the rod and main ?

These are for RB26, I doubt that RB25 will be different but I don't have a manual for that engine.

Crank is 0.028-0.046mm (0.0011-0018 inches)

Conrod is 0.020-0.039mm (0.0008-0016 inches)

It's actually a bit more complicated than that because main and conrod journals/tunnels/rods are graded at the factory and then bearing thicknesses are selected to get the correct clearance.      OTOH, with an aftermarket set of shells it's all one size, although there would be a very small variation due to manufacturing tolerances.   

In your case, if you're confident the journals are in good condition (short of actually measuring them with a mic....not vernier and most people don't have access to the specialist bore gauges required for main tunnels and rods) and you have the original bearing shells still in their original locations on the rods and block, you can measure the clearance with plastiguage, which will be a reasonable guide to the condition of the bearings/journals.     

 

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