oil pressure/ bearing clearance

[oldgold]

does bearing clearance dictate the type of oil pump you would run
i know that clearances should be about 2.5 to 3thousandths but would you run a stock pump on bearing clearances that are a little less or would a engine with 2 to 2.5 spin the bearings. 350 based cast crank/rods 6.000 rpm.

[rubbinsracin]

we always run high volume pump with a high volume pickup with an 8qt pan to make sure we never suck it dry. we have never had oiling problems. i was always under the understanding that once your clearance gets to 25 or 30 you should be good with a hv pump

[oldgold]

we always run high volume pump with a high volume pickup with an 8qt pan to make sure we never suck it dry. we have never had oiling problems. i was always under the understanding that once your clearance gets to 25 or 30 you should be good with a hv pump my only concern was i bought a fresh shortblock from a racer who sold the car. never fired. bearing clearances were 2.5 on mains and 2.0 on rods .put a m-77 pump on it ran about 10 laps and developed a oil pressure problem pulled it off and out of the car bearings down to copper but not spun .fresh bearings ran break in developed a rattle spun rod bearing,
my thought was to much oil pressure or pumped oil to top of engine
starving bearings. will a engine with that close of tolerances run ok or is this a disaster

[Egoracing]

Make sure the oil galley plugs are all in place. If someone forgot one of them or damaged one putting it in..... A racer had one motor eat 3 sets of bearings and asked me to come check it out and the galley plugs behind the timing chain were drilled and tapped and they put regular freeze plugs in not knowing and it popped them out and was dumping the oil back into the pan and they had pressure, they were using a high pressure/volume pump and it kept the gauge from hitting zero.

[ford396]

.0025 on mains and .002 on rods is a good target in my opinion. I do not think your problem is related to incorrect oil pump. I would be looking elsewhere. Egoracing brings up a good point about oil galley plugs. It is also possible that someone forgot the plug under the main cap that diverts the oil through the filter: thereby not filtering the oil at all.

I would also question if the block was properly cleaned after the first failure. If any foreign material were too be left in the block, new bearings would fail rather quickly. Also ensure that oil drain back holes are enlarged and free flowing.