Hi everyone, im in the middle still of building my duratec engine. My supertech pistons arrived so I decided to strip the engine down (I recently built it but with the wrong pistons). The crank has scored the lower bearings on the rods but I cant feel the marks with my finger but only ever so slightly with my fingernail. These were quite expensive tri-metal bearings and if the bearings are ok then great but if not then its rather annoying! What are peoples thoughts?
I have since ground the oil journals as I felt a lip on them.

Do bearings have a protective coating which this might be? Many thanks

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I would change the bearing and get the crank checked .

As above, Check the size of the bearings, Check the crank and rebuild it checking with Plastigauge and fit new bearings.

It might just be that the crank only needs a polish. I'd also check the oilway holes in the crank and make sure everything is cleaner than clean and there is no possibility of oil contamination.

Those bearings look like they have 'picked up' due to contamination and/or scoring.


Is the scoring just on the lower half of the big end bearing ? What does the upper half look like ?

Upper halves are fine. I checked the bearing clearances with plastigauge and all was well. The crank was balanced and checked by an experienced engine builder but I guess missed the little ridges I felt in the oil holes

Sorry can't help on the bearing issue, but I too have my Duratec in pieces. Just wondering what comp ratio the pistons you first used were (I think in an earlier post you mentioned they were cosworth).

Which Supertech pistons have you gone for, the 12.5s?

Thanks James

That's not good, You don't want sharp edges on the oilway holes in the crank as they will 'cut in' to the bearing material

Hi James. Yes the 12.5 supertech is what I've gone for. Quite a few others have so fugured it must be Ok for me too. The cosworth ones had too close piston to valve clearances as I'm using quite big cams.

Thanks for the info. Hope the rest of the build goes a bit more smoothly. Keep us posted!


Cheers James