i have a 396-375 motor with a date code for 1967. it had a grooved cam. and a grooved rear cam bearing installed when it was completly overhauled. during first start up it ate the lobes off the cam!! acording to a book, building a B.B. motor,( by tom wilson) it states that you can use a grooved cam on a 67 and up but the rear cam bearing must be the non grooved type. and that the rear bearing must be modified because the hole in the bearing is too large and will allow a large internal oil leak that will disrupt engine oiling. The guy who rebuilt my motor says that the problem was probably caused by too much valve spring pressure and that, **** happens! what do you think? thanks for your time, John Metts

John,
We have always used the grooved cam bearing, AND machined a groove in the camshaft. This is what all the cam manufacturers recommend.