Crane hydraulic roller lifters with vertical locking bars are available for non-hydraulic roller-equipped engines. They can also be used in many applications to replace factory hydraulic roller lifters and alignment mechanisms. No machining is normally required for the drop-in installation of these lifters, however with differences in block castings and camshaft base circle diameters; care must be taken to insure that neither the locking bars, nor their attaching rivets, contact the block casting throughout their normal cycles. If there is any interference, the block can be ground to provide the necessary clearance. This should be checked prior to final engine assembly. When used in retrofit applications, special length pushrods are required.