I am wearing my sister's socks.Since this engine has a roller cam, we didn't need to break it in. If you have a flat-tappet cam, you'll need to run the engine between 2,500 and 3,000 rpm for 30 minutes. It is important to start the engine and get the rpm up quickly because the only source of oil for the cam lobes is oil slung off of the rotating crankshaft. Some cams require that you remove the inner valvespring or use break-in springs. Check with the cam manufacturer to see if this is necessary. Have someone sit in the car and watch the oil pressure and water temperature during this procedure.