These heads are about 5-6 years old were ported by modern cyl head and had tons of passes on them and had crane rockers we freshened the heads and the guides and valves were beat to death and the engine was always having valve train issues breaking rocker arms and such I bought the engine this way from a friend when we replaced the valves we measured the old valves and bought the same size I relly feel the rocker pedastal casting on this one set of heads is just not correct I think the harland sharp rocker is too long and the crane rocker was too short causing guide/valve wear I have a newer set of SR heads on another motor that harland sharp rockers came off of and had no issues by the way the new heads were cnc ported by indy and are not even close to the older set done by modern the old set are better flowing heads from .100 to .800