Maybe a couple lifters collapsed or not pumping up ? In my valiant I have a comp 260 cam (hydraulic flat tappet) and 273 rockers and its quite as a mouse. The 360 that Bob Lambeck built for my barracuda
has a custom grind hydraulic roller cam with johnson roller lifters and comp ductile iron rockers. It sounds like a sewing machine ( but hauls serious *** ) Have you tried pushing down on the pushrod side of the rocker after its warmed up to check for lifters that aren't pumping up ? Call Crane and ask how much preload they the want for the lifters. Johnson wants .035 plus or minus .010
