Had a mechanic install a used replacement B21F engine. Cylinders checked ok so honed cylinders and installed new rings and bearings. Now the engine has a 1 or 2 second rattle at startup (rather loud when cold and slight when hot after sitting for several minutes), and the oil pressure light glows flickers at idle (approximately 900 RPM with A/C engaged). I do not notice a noise at idle when the oil light flickers. The start-up noise doesn't sound like the deep knock of a rod knock but I haven't listened to see where it specifically coming from. I also haven't noticed a noise other than lifter click at speed and the oil light goes out with a slight accelerator pressure. If I increase the idle any more it will idle too high in park. Puralator oil filter, 5w50 oil for breakin. Have put about 175 miles on engine. Have not checked oil pressure with a gauge. Thanks in advance. B.