LS lifters features flats on the upper body. These register into the plastic lifter buckets to maintain lifter orientation, preventing lifter rotation.
The clever aspect of the LS lifter buckets and their location is that this design allows you to perform a future camshaft change without the need to remove the intake manifold or the lifters. Simply loosen the rockers, remove the pushrods, and turn the camshaft one full revolution. This will nudge the lifters back into the buckets to the point where they’ll stay “stuck” in the bucket bores and away from the cam lobes. The camshaft can then be removed/installed without the need to remove the lifters and buckets.
This is one of the very cool advantages of the LS lifter design, allowing camshaft service without the need to remove the intake manifold and lifters (as in previous engine generations).
NOTE: While “popping” the lifters fully upward into their bucket retainers should secure the lifters away from the camshaft, you must avoid allowing any of the lifters from accidentally dropping (this would require removal of the cylinder heads, cylinder head gaskets and lifter buckets in order to then retrieve the dropped lifter(s)).
Roller-tipped lifters must be kept in plane with the cam lobes to allow the roller to glide over the cam lobe. If the lifter body is allowed to rotate in its bore, both lifter and lobe will be destroyed.
In order to absolutely ensure that this won’t occur, you can temporarily insert a pair of 1/4-inch or 5/16-inch-diameter rods (about 22 inches long each) into the oil galley holes that are adjacent to the camshaft bore, accessed at the front of the engine block (these are exposed once the front engine cover is removed, which is necessary in order to perform a camshaft change anyway). These rods will prevent any lifters from accidentally dropping through their bores. Once the camshaft has been reinstalled, simply remove these rods. CAUTION: When inserting these rods, install them gently. If you bottom them out with any degree of force, you might disturb the oil plugs at the rear of the block.
Inspect the lifter rollers for cleanliness and for smooth operation. If chatter marks are found on the rollers, this is a sign that the lifter bearing may have been sticking, in which case the camshaft should also be inspected. If chatter marks are found on either the lifter roller or the cam lobe, replace the errant component.
As with any hydraulic lifter, check each roller lifter for cleanliness, including the critical oil passage.
With the group of four lifters entering their respective lifter bores, allow the retention/guide bucket to rest onto the block mounting surface.
If aftermarket lifters are taller than OEM lifters, it will be necessary to raise the lifter buckets. A spacer washer (this should be supplied with the lifters) is located between the lifter bucket and cylinder head surface.