Bearing Clearance

What i meant was check the size of the crank journals with a micrometer and refer to the manual for the minimum allowable size of a standard unground journal and also check for ovality/ out of round, then if your measurements are different (smaller) to what is in the manual you will know for sure that your crank has been previously ground undersize to suit undersize bearings mate, then you can work out which bearings you need, either standard size or undersize, hope that makes sense mate.

Filing shells down makes no difference to real dynamic clearances, all that does is reduce crush load and that what stop shell spinning so you want that kept in spec.
Also be careful using plasti gauge, bearings are oval and need measuring in cap axis as well as across cap axis, you want internal mic them and leave plastigauge to final crank fit check only
So what acl bearings you got ! they do standard in H & HX,
HX giving more clearance over H
Can be pain with acl on cranks that been polished bit heavily.
You may get some luck by doing measurements then juggle shells around on tighter ones to sloppy ones in attempt reduce/even clearances.
sometimes a regrind is easier as if machinist real good he can get it spot on preferred clearance range with grinding/polishing.
If you have not fully checked crank for cracks, straightness & journal ovality then needs doing as issues here could mean changing action to new crank or journal grind perhaps ...

yes its a real problem with what clearance to aim for on performance cars because if you take the smaller clearance and the runout is out of spec then this will cause you problems further down the line with excessive main bearing wear

yet if you go for a larger clearance you then require a very good oil flow to hold the pressure especially when the oil is hot, if you haven't got this then once again it can lead to problems.

a good crank is the key to having a good long lasting build as can rapidly destroy your entire engine if its out of spec, poor mapping with excess over fuelling will also rapidly help it on its way due to oil viscosity breaking down when hot so its paramount that you get this bit right and I personally would go for a mid range clearance

Right so bearings are standard h

what i though Chris had in mind id to measure crank and go with chart for genuine bearings (all the colours depending on grade of bearing etc)
and the story with this crank/engine is very long but it was apparently checked and it was balanced and it's standard size (bloody thing look spotless) so the problem might be in that i'm trying to get clearances for new crank ( i was aiming for 0.02mm)
like i said before i've plastigauged all mains and they came up pretty much 0.05mm so i'm just wandering shall i try to go down more and if yes what clearance shall i go for?