So.....

All you old school guys with all sorts of tricks up our sleaves, what type of clearances do you run on rod bearings when building a race motor?

Rich

What weight oil?? What journal diameter? What oil pump? Revs?

20/50, 2.0 liter stock, stock pump....up to 6k max

For me it's the run-out (like end play) of the rod big end on the journal, the tighter the spec and you will get better oil pressure. Many stock 2.0 rods I've seen are already past the stock tolerance, so check all your sets. Also will allow you to cut oil groves into the rod with less pressure loss. Some guys will radius the bearing a bit more.

Use quality bearings.

I would run .002 radial clearance on this, but thats not a recommendation!! I have been experimenting with all sorts of different clearances and I tend to keep the rods tighter than most people, but then open the mains up a tad more for better oil transition into the rod bearings.. Tight mains reduce oil volume to the rod bearings.

Things change when you start turning over 7K constantly..

Well If I am anything I,m old school. and having built Many porsche racing engines(75+) in the last 35 years.....here,s what you should do..1)..get your crankshaft cross-drilled. 2) USE the cast iron MELLING oil pump...(and throw away that stock piece of crap) 3) use any clearances up to .003ths inch total...and if the clearances are below .001ths...polish the hell out of the crank, or find another bearing(s) set. note kolbenschmidts tend to be on the tight side.(less clearance). 4)always use 20-50 oil which you do ...5) use all the high side factory clearances...crank end play especially..6) you can adjust oil pressure, if your oil pressure is low,at Idle when hot....but it,s a race engine right! so it won't be idling much...use loose clearances and free up your horsepower.,and expect a shorter lifespan before rebuilding...again...

Melling oil pump