Duane
Well-Known Member
Here is a theory I have but cannot prove. Does an engine oil pump pressure feed the rod bearing or does the centrifugal force of the spinning crankshaft throw the oil in the crank oil cavity at the rod bearings. This was Sanborns theory that the slotting of main bearings gave a longer dwell time for that passage to fill up.I get what your saying. My issue is I never failed the 5-6 rod bearings, and I’ve never seen anyone else. It’s always the 3-4 rods. In fact, my first 2 X block came real cheap because he kicked the 3-4 rods off both and quit racing over it. I offered to have him send them to me, and I’d fix the issues but he was done. His loss, my gain. A couple of sleeves and they went into service.
So that can’t be a velocity issue. If you’ve ever seen say...a long string of sprinklers in a field, like 30 or so where you get look at the system filling up, you’ll see the last 2 or 3 sprinkler heads and the first 20 or so will all be at full load while those at the far end that are 3-5 are the very last to get to full flow. Once they are all flowing, the nozzle is the limit. Pretty much what happens in an oiling system.
I ask this because I have had failed 2&4 main bearings with no sign of rod bearing damage. It was explained to me that because I did not restrict oil going to the rockers, my main bearing oil did not form hydro dynamic wedge because of inadequate pressure, yet I saw no signs of rod bearing trouble. Could it be that because the crank passage was filled but not pressurized, that centrifugal force still adequately supplied the rods?