I'll try and keep this brief! sorry if it is hard to follow i just picking out the important bits
I'm building an ej engine, crank ground .25mm on bigs and mains, king bearings, all big end clearances checked and are spot on .050mm
Assembled (oiled) crank into casings, torqued case bolts (8) it was harder than expected to rotate, i was expecting near to no resistance, but got some, so stripped down and inspected, the no1 bearing has visible wear on the forward edge, it was black but now silver.
The no1 main bearings have a forward and aft face separated by an oil way, a clearance check showed it .03mm on the forward side and 0.05 on the aft side, all other main clearances 0.05mm.
I was not expecting to see wear on the bearing after just a few revolutions of the crank, and never have in any other engine build I have done. I appreciate that the bearings do wear and bed in, but is this usual to see at this stage? And is it usual for the crank to 'free up' as the bearings bed in? First time I've used king bearings and they're a different colour to ACL's, could this be why I have never noticed any marking on bearings before?!
Cheers

 

Take all your bearings out, bolt it all back together, torque up, & measure the main bearing tunnel, it may well be out of round, the bearings only follow the shape of the block tunnel, plus there is 10 bolts not 8, & your using a reground crank, sure the journals are all concentric, & inline.


Also you may have debris fallen into the void upon fitting the two block halves together.

 

Thanks for the reply

You are 100% correct there are 10 main case bolts, and I fitted 10, but I typed 8! EDIT! lol

0.1mm ~ish (crudely measured by verniers) difference in DIA vertically opposed to horizontally in the bore causing concern, i'll try and measure more accurately ASAP

I'm getting consistent clearance results both sides which implies the crank is concentric

 

No it won't be 0.1m, you would never turn it if its that out of round, check for any dings or high spots on the bearing face in the block, you will only need 0.0127mm & it will feel tight, especially if your doing it in the current cold weather.


You will need at least a bore micrometer, but really bore dial gauge.

 

yea, like i said crude measurement using vernier, havnt got the equipment to measure accurately but will get it. And i'll have a good look at the bearing face of the block to make sure there is nothing obvious

building it in front room, so constant 20deg ish

Thanks for the help nailing the cause

 

no1 main was 1/2 thou out