This is main bearing from my friends engine. Something is wrong, but what? It has some brown colour and little spots in it, and in some areas the tin surface has been flaking off. Clearances are fine, .0025" rods and .003" mains.
Could too hot oil, or some kind of oil pump cavitation problem cause this? My friend doesnīt run oil temp gauge, but oil pressure has been dropping in some cases, like in highway with engine running 5000 rpms, indicating that oil is getting too hot. He does run B&M 5 x 11" oil cooler. Itīs a sbc engine with hv oilpump in it, and he has been told that the hv pump is causing a cavitation problem, and that he needs smaller volume pump with some kind of anti-cavitation grooves. Does this sound right to you?
